Systems and methods for controlling fluid instillation therapy using ph feedback

ABSTRACT

Systems, apparatuses, and methods for providing negative pressure with instillation fluids to a tissue site are disclosed. Some embodiments are illustrative of an apparatus or system for delivering negative-pressure and/or therapeutic solution of fluids to a tissue site, which can be used in conjunction with sensing properties of fluids extracted from a tissue site and/or instilled at a tissue site. For example, a system may comprise a tissue interface adapted to be coupled to a source of instillation fluid and a dressing interface having a therapy cavity that includes a pH sensor to provide data indicative of acidity/alkalinity at the tissue site. Such apparatus may further comprise algorithms for processing such data for providing information relating to the progression of healing of wounds at the tissue site.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Provisional Application No. 62/960,992, filed on Jan. 14, 2020, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The invention set forth in the appended claims relates generally to tissue treatment systems and more particularly, but without limitation, to systems and methods for providing negative-pressure therapy with fluid instillation therapy and sensing properties of wound exudates extracted from a tissue site.

BACKGROUND

Clinical studies and practice have shown that reducing pressure in proximity to a tissue site can augment and accelerate growth of new tissue at the tissue site. The applications of this phenomenon are numerous, but it has proven particularly advantageous for treating wounds. Regardless of the etiology of a wound, whether trauma, surgery, or another cause, proper care of the wound is important to the outcome. Treatment of wounds or other tissue with reduced pressure may be commonly referred to as “negative-pressure therapy,” but is also known by other names, including “negative-pressure wound therapy,” “reduced-pressure therapy,” “vacuum therapy,” “vacuum-assisted closure,” and “topical negative-pressure,” for example. Negative-pressure therapy may provide a number of benefits, including migration of epithelial and subcutaneous tissues, improved blood flow, and micro-deformation of tissue at a wound site. Together, these benefits can increase development of granulation tissue and reduce healing times.

There is also widespread acceptance that cleansing a tissue site can be highly beneficial for new tissue growth. For example, a wound can be washed out with a stream of liquid solution, or a cavity can be washed out using a liquid solution for therapeutic purposes. These practices are commonly referred to as “irrigation” and “lavage” respectively. “Instillation” is another practice that generally refers to a process of slowly introducing fluid to a tissue site and leaving the fluid for a prescribed period of time before removing the fluid. For example, instillation of topical treatment solutions over a wound bed can be combined with negative-pressure therapy to further promote wound healing by loosening soluble contaminants in a wound bed and removing infectious material. As a result, soluble bacterial burden can be decreased, contaminants removed, and the wound cleansed.

While the clinical benefits of negative-pressure therapy and instillation therapy are widely known, improvements to therapy systems, components, and processes may benefit healthcare providers and patients.

BRIEF SUMMARY

New and useful systems, apparatuses, and methods for instilling fluid to a tissue site in a negative-pressure therapy environment are set forth in the appended claims. Illustrative embodiments are also provided to enable a person skilled in the art to make and use the claimed subject matter. Some embodiments are illustrative of an apparatus or system for delivering negative-pressure and therapeutic solution of fluids to a tissue site, which can be used in conjunction with sensing properties of wound exudates extracted from a tissue site. For example, an apparatus may include a pH sensor, a humidity sensor, a temperature sensor and a pressure sensor embodied on a single pad proximate the tissue site to provide data indicative of acidity, humidity, temperature and pressure. Such apparatus may further comprise an algorithm for processing such data for detecting leakage and blockage as well as providing information relating to the progression of healing of wounds at the tissue site.

In some embodiments, for example, a system for controlling negative pressure and instillation therapy at a tissue site based on properties of wound fluids, wherein the system may comprise a tissue interface adapted to be disposed at the tissue site and adapted to be coupled to a source of instillation fluid. The system may further comprise a dressing interface adapted to couple a source of negative-pressure to the tissue interface, wherein the dressing interface comprises a housing having a therapy cavity including an opening configured to be disposed in fluid communication with the tissue interface, and a negative-pressure port adapted to fluidly couple the therapy cavity to the source of negative-pressure. The dressing interface may further comprise a pH sensor in fluid communication with the therapy cavity and configured to sense pH of the wound fluids. The system may also comprise a processing element electrically coupled to the pH sensor for receiving a property signal indicative of the pH of the wound fluids. The processing element may be configured further to assess the health characteristics of the tissue site based on the pH of the wound fluids and modify the instillation therapy in response to the pH measured.

The pH sensor may be disposed within the therapy cavity adjacent to the tissue interface. In some embodiments, the pH sensor may be disposed within the therapy cavity adjacent to the tissue site. In yet some other embodiments, the pH sensor may be disposed in a conduit between the negative-pressure port and the source of negative-pressure. In still other embodiments, the pH sensor may be disposed in a canister between the negative-pressure port and the source of negative-pressure. The dressing interface may further comprise a second pH sensor in fluid communication with a conduit between the negative-pressure port and the source of negative-pressure. In yet other embodiments, the second pH sensor may be in fluid communication with a canister between the negative-pressure port and the source of negative-pressure. The dressing interface may further comprise a third pH sensor in fluid communication with the source of instillation fluid and configured to sense pH of the instillation fluid.

In some embodiments, the system may further comprise a controller configured to receive the property signals from the processing element and to assess property readings reflective of the property signals to identify the health characteristics of the system. The system may further comprise a transmitter configured to transmit the property signals to the controller. The system may further comprise an instillation pump configured to provide instillation fluid to the tissue interface, and a sensor electrically coupled to the controller and adapted to measure an instillation pump pressure and an instillation duty cycle provided by the instillation pump.

In some embodiments, the dressing interface may further comprise a pH sensor mounted to the housing in fluid communication with the therapy cavity and configured to sense the pH of the fluids adjacent the tissue interface during instillation of liquids to the tissue interface. The processing element may be electrically coupled to the pH sensor for receiving property signals including a property signal indicative of the pH, wherein the processing element may be configured to assess the health characteristics of the tissue site. The controller may be further configured to receive the property signals indicative of the pH from the processing element and to assess property readings reflective of the property signals to identify the health characteristics of the tissue site. The processing element may be further configured to transmit the property signals indicative of the pH to the controller. The health characteristics of the system may include a wound progression state within the system, and the controller may be configured to provide an alarm indicative of the wound progression state based on the property signals. In some embodiments, the processing element is further configured to compare the pH of the wound fluids to a target pH range.

In some embodiments, the processing element is further configured to modify the instillation therapy by adjusting the dwell time of instillation fluid delivered to the tissue site. In some other embodiments, the processing element is further configured to modify the instillation therapy by adjusting the soak time of instillation fluid delivered to the tissue site. In yet other embodiments, the processing element is further configured to modify the instillation therapy by adjusting the volume of instillation fluid delivered to the tissue site.

In some embodiments, the system further comprise a second pH sensor disposed at a second location between the negative-pressure port and the source of negative-pressure, and a second processing element electrically coupled to the second pH sensor for receiving a second property signal indicative of the pH of the exudate fluids at the second location. The processing element may be configured further to assess the health characteristics of the tissue site based on the pH of the exudate fluids at the second location and modify the instillation therapy in response to the pH measured. In some other embodiments, the system further comprise a second pH sensor disposed at a second location between the therapy cavity and the source of instillation fluid, and a second processing element electrically coupled to the second pH sensor for receiving a second property signal indicative of the pH of the instillation fluids at the second location. The processing element may be configured further to assess the health characteristics of the tissue site based on the pH of the instillation fluids at the second location and modify the instillation therapy in response to the pH measured.

Some embodiments are illustrative of a method for utilizing a system for providing negative pressure with fluid instillation therapy based on assessing properties of wound fluids at the tissue site, wherein the system comprises a tissue interface and a dressing interface having a housing including a therapy cavity. In some embodiments, the method may comprise positioning the tissue interface at the tissue site, wherein the tissue interface may be adapted to be coupled to a source of instillation fluid, and positioning the therapy cavity in fluid communication with the tissue interface, wherein the therapy cavity may be adapted to be coupled to a source of negative pressure. The method may also comprise delivering instillation fluid from the source of instillation fluid to the therapy cavity. In some embodiments, the method may further comprise sensing pH of wound fluids using a pH sensor mounted to the housing in fluid communication with the therapy cavity. The method may further comprise determining the health characteristics of the system by using a processing element electrically coupled to the pH sensor, wherein the processing element receives property signals indicative of the pH measured, and then modifying the instillation therapy in response to the pH measured.

The method may further comprise transmitting the property signals to a controller within the system for assessing the health characteristics of the system and using the controller to assess assessing property readings reflective of the property signals in order to identify the health characteristics of the system. The method may further comprise sensing pH of the fluids adjacent the tissue interface during instillation of liquids to the tissue interface using a pH sensor mounted to the housing in fluid communication with the therapy cavity, and determining health characteristics of the tissue site by using a processing element mounted to the housing outside the therapy cavity and electrically coupled to the pH sensor for receiving property signals indicative of the pH of the wound fluids.

Objectives, advantages, and a preferred mode of making and using the claimed subject matter may be understood best by reference to the accompanying drawings in conjunction with the following detailed description of illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram of an example embodiment of a therapy system that can provide negative-pressure and instillation in accordance with this specification;

FIG. 2 is a schematic diagram illustrating additional details that may be associated with an example embodiment of the therapy system of FIG. 1 ;

FIG. 3A is a graph illustrating an illustrative embodiment of pressure control modes for the negative-pressure and instillation therapy system of FIG. 1 wherein the x-axis represents time in minutes (min) and/or seconds (sec) and the y-axis represents pressure generated by a pump in Ton (mmHg) that varies with time in a continuous pressure mode and an intermittent pressure mode that may be used for applying negative pressure in the therapy system;

FIG. 3B is a graph illustrating an illustrative embodiment of another pressure control mode for the negative-pressure and instillation therapy system of FIG. 1 wherein the x-axis represents time in minutes (min) and/or seconds (sec) and the y-axis represents pressure generated by a pump in Torr (mmHg) that varies with time in a dynamic pressure mode that may be used for applying negative pressure in the therapy system;

FIG. 3C is a schematic block diagram showing an illustrative embodiment of a therapy method for providing negative-pressure and instillation therapy for delivering treatment solutions to a dressing at a tissue site;

FIG. 4 is a sectional side view of a dressing interface comprising a housing and a wall disposed within the housing and forming a therapy cavity including sensors and a component cavity including electrical devices that may be associated with some example embodiments of the therapy system of FIG. 1 ;

FIG. 5A is a perspective top view of the dressing interface of FIG. 4 , FIG. 5B is a side view of the dressing interface of FIG. 4 disposed on a tissue site, and FIG. 5C is an end view of the dressing interface of FIG. 4 disposed on the tissue site;

FIG. 6A is an assembly view of the dressing interface of FIG. 4 comprising components of the housing and a first example embodiment of a sensor assembly including the wall, the sensors, and the electrical devices;

FIG. 6B is a system block diagram of the sensors and electrical devices comprising the sensor assembly of FIG. 6A;

FIGS. 7A, 7B and 7C are a top view, side view, and bottom view, respectively, of the sensor assembly of FIG. 6 ;

FIG. 7D is a perspective top view of the sensor assembly of the sensor assembly of FIG. 6 including one example embodiment of a pH sensor;

FIG. 8A is a perspective bottom view of the dressing interface of FIG. 4 , and FIG. 8B is a bottom view of the dressing interface of FIG. 4 ;

FIG. 9A is a top view of a first embodiment of a pH sensor that may be used with the sensor assembly of FIG. 8D, and FIG. 9B is a top view of a second embodiment of a pH sensor that may be used with the sensor assembly of FIG. 8D;

FIG. 10 is a flow chart illustrating a method for treating a tissue site utilizing the dressing interface of FIG. 4 for applying negative-pressure therapy with fluid instillation and sensing properties of wound exudates extracted from the tissue site;

FIG. 11 is a schematic block diagram illustrating a negative pressure control algorithm utilized within the tissue treatment method of FIG. 10 including the detection of dressing flow characteristics within the system and the assessment of sensor properties;

FIG. 12 is a block diagram of a user interface illustrating alerts and alarms associated with the dressing flow characteristics of FIG. 11 ;

FIG. 13 is a flow chart illustrating a wound pressure control method configured to operate in the negative pressure control algorithm of FIG. 11 ;

FIG. 14 is a schematic block diagram illustrating a fluid instillation control algorithm utilized within the tissue treatment method of FIG. 10 including the detection of dressing flow characteristics within the system and the assessment of sensor properties and dispensed volume; and

FIG. 15 is a flow chart illustrating a method for detecting blockages and fluid leaks as two of the dressing flow characteristics of FIG. 14 .

DESCRIPTION OF EXAMPLE EMBODIMENTS

The following description of example embodiments provides information that enables a person skilled in the art to make and use the subject matter set forth in the appended claims, but may omit certain details already well-known in the art. The following detailed description is, therefore, to be taken as illustrative and not limiting.

The example embodiments may also be described herein with reference to spatial relationships between various elements or to the spatial orientation of various elements depicted in the attached drawings. In general, such relationships or orientation assume a frame of reference consistent with or relative to a patient in a position to receive treatment. However, as should be recognized by those skilled in the art, this frame of reference is merely a descriptive expedient rather than a strict prescription.

The term “tissue site” in this context broadly refers to a wound, defect, or other treatment target located on or within tissue, including but not limited to, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. A wound may include chronic, acute, traumatic, subacute, and dehisced wounds, partial-thickness burns, ulcers (such as diabetic, pressure, or venous insufficiency ulcers), flaps, and grafts, for example. The term “tissue site” may also refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it may be desirable to add or promote the growth of additional tissue. For example, negative pressure may be applied to a tissue site to grow additional tissue that may be harvested and transplanted.

The present technology also provides negative pressure therapy devices and systems, and methods of treatment using such systems with antimicrobial solutions. FIG. 1 is a simplified functional block diagram of an example embodiment of a therapy system 100 that can provide negative-pressure therapy with instillation of treatment solutions in accordance with this specification. The therapy system 100 may include a negative-pressure supply, and may include or be configured to be coupled to a distribution component, such as a dressing. In general, a distribution component may refer to any complementary or ancillary component configured to be fluidly coupled to a negative-pressure supply between a negative-pressure supply and a tissue site. A distribution component is preferably detachable, and may be disposable, reusable, or recyclable. For example, a dressing 102 is illustrative of a distribution component that may be coupled to a negative-pressure source and other components. The therapy system 100 may be packaged as a single, integrated unit such as a therapy system including all of the components shown in FIG. 1 that are fluidly coupled to the dressing 102. The therapy system may be, for example, a V.A.C. Ulta™ System available from Kinetic Concepts, Inc. of San Antonio, Texas.

The dressing 102 may be fluidly coupled to a negative-pressure source 104. A dressing may include a cover, a tissue interface, or both in some embodiments. The dressing 102, for example, may include a cover 106, a dressing interface 107, and a tissue interface 108. A computer or a controller device, such as a controller 110, may also be coupled to the negative-pressure source 104. In some embodiments, the cover 106 may be configured to cover the tissue interface 108 and the tissue site, and may be adapted to seal the tissue interface and create a therapeutic environment proximate to a tissue site for maintaining a negative pressure at the tissue site. In some embodiments, the dressing interface 107 may be configured to fluidly couple the negative-pressure source 104 to the therapeutic environment of the dressing. The therapy system 100 may optionally include a fluid container, such as a container 112, fluidly coupled to the dressing 102 and to the negative-pressure source 104.

The therapy system 100 may also include a source of instillation solution, such as a solution source 114. A distribution component may be fluidly coupled to a fluid path between a solution source and a tissue site in some embodiments. For example, an instillation pump 116 may be coupled to the solution source 114, as illustrated in the example embodiment of FIG. 1 . The instillation pump 116 may also be fluidly coupled to the negative-pressure source 104 such as, for example, by a fluid conductor 119. In some embodiments, the instillation pump 116 may be directly coupled to the negative-pressure source 104, as illustrated in FIG. 1 , but may be indirectly coupled to the negative-pressure source 104 through other distribution components in some embodiments. For example, in some embodiments, the instillation pump 116 may be fluidly coupled to the negative-pressure source 104 through the dressing 102. In some embodiments, the instillation pump 116 and the negative-pressure source 104 may be fluidly coupled to two different locations on the tissue interface 108 by two different dressing interfaces. For example, the negative-pressure source 104 may be fluidly coupled to the dressing interface 107 while the instillation pump 116 may be fluidly to the coupled to dressing interface 107 or a second dressing interface 117. In some other embodiments, the instillation pump 116 and the negative-pressure source 104 may be fluidly coupled to two different tissue interfaces by two different dressing interfaces, one dressing interface for each tissue interface (not shown).

The therapy system 100 also may include sensors to measure operating parameters and provide feedback signals to the controller 110 indicative of the operating parameters properties of fluids extracted from a tissue site. As illustrated in FIG. 1 , for example, the therapy system 100 may include a pressure sensor 120, an electric sensor 124, or both, coupled to the controller 110. The pressure sensor 120 may be fluidly coupled or configured to be fluidly coupled to a distribution component such as, for example, the negative-pressure source 104 either directly or indirectly through the container 112. The pressure sensor 120 may be configured to measure pressure being generated by the negative-pressure source 104, i.e., the pump pressure (PP). The electric sensor 124 also may be coupled to the negative-pressure source 104 to measure the pump pressure (PP). In some example embodiments, the electric sensor 124 may be fluidly coupled proximate the output of the output of the negative-pressure source 104 to directly measure the pump pressure (PP). In other example embodiments, the electric sensor 124 may be electrically coupled to the negative-pressure source 104 to measure the changes in the current in order to determine the pump pressure (PP).

Distribution components may be fluidly coupled to each other to provide a distribution system for transferring fluids (i.e., liquid and/or gas). For example, a distribution system may include various combinations of fluid conductors and fittings to facilitate fluid coupling. A fluid conductor generally includes any structure with one or more lumina adapted to convey a fluid between two ends, such as a tube, pipe, hose, or conduit. Typically, a fluid conductor is an elongated, cylindrical structure with some flexibility, but the geometry and rigidity may vary. Some fluid conductors may be molded into or otherwise integrally combined with other components. A fitting can be used to mechanically and fluidly couple components to each other. For example, a fitting may comprise a projection and an aperture. The projection may be configured to be inserted into a fluid conductor so that the aperture aligns with a lumen of the fluid conductor. A valve is a type of fitting that can be used to control fluid flow. For example, a check valve can be used to substantially prevent return flow. A port is another example of a fitting. A port may also have a projection, which may be threaded, flared, tapered, barbed, or otherwise configured to provide a fluid seal when coupled to a component.

In some embodiments, distribution components may also be coupled by virtue of physical proximity, being integral to a single structure, or being formed from the same piece of material. Coupling may also include mechanical, thermal, electrical, or chemical coupling (such as a chemical bond) in some contexts. For example, a tube may mechanically and fluidly couple the dressing 102 to the container 112 in some embodiments. In general, components of the therapy system 100 may be coupled directly or indirectly. For example, the negative-pressure source 104 may be directly coupled to the controller 110, and may be indirectly coupled to the dressing interface 107 through the container 112 by conduit 126 and conduit 130. The pressure sensor 120 may be fluidly coupled to the dressing 102 directly (not shown) or indirectly by conduit 121 and conduit 122. Additionally, the instillation pump 116 may be coupled indirectly to the dressing interface 107 through the solution source 114 and the instillation regulator 115 by fluid conductors 132, 134 and 138. Alternatively, the instillation pump 116 may be coupled indirectly to the second dressing interface 117 through the solution source 114 and the instillation regulator 115 by fluid conductors 132, 134 and 139.

The fluid mechanics of using a negative-pressure source to reduce pressure in another component or location, such as within a sealed therapeutic environment, can be mathematically complex. However, the basic principles of fluid mechanics applicable to negative-pressure therapy and instillation are generally well-known to those skilled in the art, and the process of reducing pressure may be described illustratively herein as “delivering,” “distributing,” or “generating” negative pressure, for example.

In general, exudates and other fluids flow toward lower pressure along a fluid path. Thus, the term “downstream” typically implies something in a fluid path relatively closer to a source of negative pressure or further away from a source of positive pressure. Conversely, the term “upstream” implies something relatively further away from a source of negative pressure or closer to a source of positive pressure. Similarly, it may be convenient to describe certain features in terms of fluid “inlet” or “outlet” in such a frame of reference. This orientation is generally presumed for purposes of describing various features and components herein. However, the fluid path may also be reversed in some applications (such as by substituting a positive-pressure source for a negative-pressure source) and this descriptive convention should not be construed as a limiting convention.

“Negative pressure” generally refers to a pressure less than a local ambient pressure, such as the ambient pressure in a local environment external to a sealed therapeutic environment provided by the dressing 102. In many cases, the local ambient pressure may also be the atmospheric pressure at which a tissue site is located. Alternatively, the pressure may be less than a hydrostatic pressure associated with tissue at the tissue site. Unless otherwise indicated, values of pressure stated herein are gauge pressures. Similarly, references to increases in negative pressure typically refer to a decrease in absolute pressure, while decreases in negative pressure typically refer to an increase in absolute pressure. While the amount and nature of negative pressure applied to a tissue site may vary according to therapeutic requirements, the pressure is generally a low vacuum, also commonly referred to as a rough vacuum, between −5 mm Hg (−667 Pa) and −500 mm Hg (−66.7 kPa). Common therapeutic ranges are between −75 mm Hg (−9.9 kPa) and −300 mm Hg (−39.9 kPa).

A negative-pressure supply, such as the negative-pressure source 104, may be a reservoir of air at a negative pressure, or may be a manual or electrically-powered device that can reduce the pressure in a sealed volume, such as a vacuum pump, a suction pump, a wall suction port available at many healthcare facilities, or a micro-pump, for example. A negative-pressure supply may be housed within or used in conjunction with other components, such as sensors, processing units, alarm indicators, memory, databases, software, display devices, or user interfaces that further facilitate therapy. For example, in some embodiments, the negative-pressure source 104 may be combined with the controller 110 and other components into a therapy unit. A negative-pressure supply may also have one or more supply ports configured to facilitate coupling and de-coupling the negative-pressure supply to one or more distribution components.

The tissue interface 108 can be generally adapted to contact a tissue site. The tissue interface 108 may be partially or fully in contact with the tissue site. If the tissue site is a wound, for example, the tissue interface 108 may partially or completely fill the wound, or may be placed over the wound. The tissue interface 108 may take many forms, and may have many sizes, shapes, or thicknesses depending on a variety of factors, such as the type of treatment being implemented or the nature and size of a tissue site. For example, the size and shape of the tissue interface 108 may be adapted to the contours of deep and irregular shaped tissue sites. Moreover, any or all of the surfaces of the tissue interface 108 may have projections or an uneven, course, or jagged profile that can induce strains and stresses on a tissue site, which can promote granulation at the tissue site.

In some embodiments, the tissue interface 108 may be a manifold such as manifold 408 shown in FIG. 4 . A “manifold” in this context generally includes any substance or structure providing a plurality of pathways adapted to collect or distribute fluid across a tissue site under pressure. For example, a manifold may be adapted to receive negative pressure from a source and distribute negative pressure through multiple apertures across a tissue site, which may have the effect of collecting fluid from across a tissue site and drawing the fluid toward the source. In some embodiments, the fluid path may be reversed or a secondary fluid path may be provided to facilitate delivering fluid across a tissue site.

In some illustrative embodiments, the pathways of a manifold may be interconnected to improve distribution or collection of fluids across a tissue site. In some illustrative embodiments, a manifold may be a porous foam material having interconnected cells or pores. For example, cellular foam, open-cell foam, reticulated foam, porous tissue collections, and other porous material such as gauze or felted mat generally include pores, edges, and/or walls adapted to form interconnected fluid channels. Liquids, gels, and other foams may also include or be cured to include apertures and fluid pathways. In some embodiments, a manifold may additionally or alternatively comprise projections that form interconnected fluid pathways. For example, a manifold may be molded to provide surface projections that define interconnected fluid pathways.

The average pore size of a foam manifold may vary according to needs of a prescribed therapy. For example, in some embodiments, the tissue interface 108 may be a foam manifold having pore sizes in a range of 400-600 microns. The tensile strength of the tissue interface 108 may also vary according to needs of a prescribed therapy. For example, the tensile strength of a foam may be increased for instillation of topical treatment solutions. In one non-limiting example, the tissue interface 108 may be an open-cell, reticulated polyurethane foam such as GranuFoam® dressing or VeraFlo® foam, both available from Kinetic Concepts, Inc. of San Antonio, Texas.

The tissue interface 108 may be either hydrophobic or hydrophilic. In an example in which the tissue interface 108 may be hydrophilic, the tissue interface 108 may also wick fluid away from a tissue site, while continuing to distribute negative pressure to the tissue site. The wicking properties of the tissue interface 108 may draw fluid away from a tissue site by capillary flow or other wicking mechanisms. An example of a hydrophilic foam is a polyvinyl alcohol, open-cell foam such as V.A.C. WhiteFoam® dressing available from Kinetic Concepts, Inc. of San Antonio, Texas. Other hydrophilic foams may include those made from polyether. Other foams that may exhibit hydrophilic characteristics include hydrophobic foams that have been treated or coated to provide hydrophilicity.

The tissue interface 108 may further promote granulation at a tissue site when pressure within the sealed therapeutic environment is reduced. For example, any or all of the surfaces of the tissue interface 108 may have an uneven, coarse, or jagged profile that can induce microstrains and stresses at a tissue site if negative pressure is applied through the tissue interface 108.

In some embodiments, the tissue interface 108 may be constructed from bioresorbable materials. Suitable bioresorbable materials may include, without limitation, a polymeric blend of polylactic acid (PLA) and polyglycolic acid (PGA). The polymeric blend may also include without limitation polycarbonates, polyfumarates, and capralactones. The tissue interface 108 may further serve as a scaffold for new cell-growth, or a scaffold material may be used in conjunction with the tissue interface 108 to promote cell-growth. A scaffold is generally a substance or structure used to enhance or promote the growth of cells or formation of tissue, such as a three-dimensional porous structure that provides a template for cell growth. Illustrative examples of scaffold materials include calcium phosphate, collagen, PLA/PGA, coral hydroxy apatites, carbonates, or processed allograft materials.

In some embodiments, the cover 106 may provide a bacterial barrier and protection from physical trauma. The cover 106 may also be constructed from a material that can reduce evaporative losses and provide a fluid seal between two components or two environments, such as between a therapeutic environment and a local external environment. The cover 106 may be, for example, an elastomeric film or membrane that can provide a seal adequate to maintain a negative pressure at a tissue site for a given negative-pressure source. The cover 106 may have a high moisture-vapor transmission rate (MVTR) in some applications. For example, the MVTR may be at least 300 g/m{circumflex over ( )}2 per twenty-four hours in some embodiments. In some example embodiments, the cover 106 may be a polymer drape, such as a polyurethane film, that is permeable to water vapor but impermeable to liquid. Such drapes typically have a thickness in the range of 25-50 microns. For permeable materials, the permeability generally should be low enough that a desired negative pressure may be maintained. In some embodiments, the cover may be a drape such as drape 406 shown in FIG. 4 .

An attachment device may be used to attach the cover 106 to an attachment surface, such as undamaged epidermis, a gasket, or another cover. The attachment device may take many forms. For example, an attachment device may be a medically-acceptable, pressure-sensitive adhesive that extends about a periphery, a portion, or an entire sealing member. In some embodiments, for example, some or all of the cover 106 may be coated with an acrylic adhesive having a coating weight between 25-65 grams per square meter (g.s.m.). Thicker adhesives, or combinations of adhesives, may be applied in some embodiments to improve the seal and reduce leaks. Other example embodiments of an attachment device may include a double-sided tape, paste, hydrocolloid, hydrogel, silicone gel, or organogel.

In some embodiments, the dressing interface 107 may facilitate coupling the negative-pressure source 104 to the dressing 102. The negative pressure provided by the negative-pressure source 104 may be delivered through the conduit 130 to a negative-pressure interface, which may include an elbow portion. In one illustrative embodiment, the negative-pressure interface may be a T.R.A.C.® Pad or Sensa T.R.A.C.® Pad available from KCI of San Antonio, Texas. The negative-pressure interface enables the negative pressure to be delivered through the cover 106 and to the tissue interface 108 and the tissue site. In this illustrative, non-limiting embodiment, the elbow portion may extend through the cover 106 to the tissue interface 108, but numerous arrangements are possible.

A controller, such as the controller 110, may be a microprocessor or computer programmed to operate one or more components of the therapy system 100, such as the negative-pressure source 104. In some embodiments, for example, the controller 110 may be a microcontroller, which generally comprises an integrated circuit containing a processor core and a memory programmed to directly or indirectly control one or more operating parameters of the therapy system 100. Operating parameters may include the power applied to the negative-pressure source 104, the pressure generated by the negative-pressure source 104, or the pressure distributed to the tissue interface 108, for example. The controller 110 is also preferably configured to receive one or more input signals, such as a feedback signal, and programmed to modify one or more operating parameters based on the input signals.

Sensors, such as the pressure sensor 120 or the electric sensor 124, are generally known in the art as any apparatus operable to detect or measure a physical phenomenon or property, and generally provide a signal indicative of the phenomenon or property that is detected or measured. For example, the pressure sensor 120 and the electric sensor 124 may be configured to measure one or more operating parameters of the therapy system 100. In some embodiments, the pressure sensor 120 may be a transducer configured to measure pressure in a pneumatic pathway and convert the measurement to a signal indicative of the pressure measured. In some embodiments, for example, the pressure sensor 120 may be a piezoresistive strain gauge. The electric sensor 124 may optionally measure operating parameters of the negative-pressure source 104, such as the voltage or current, in some embodiments. Preferably, the signals from the pressure sensor 120 and the electric sensor 124 are suitable as an input signal to the controller 110, but some signal conditioning may be appropriate in some embodiments. For example, the signal may need to be filtered or amplified before it can be processed by the controller 110. Typically, the signal is an electrical signal that is transmitted and/or received on by wire or wireless means, but may be represented in other forms, such as an optical signal.

The solution source 114 is representative of a container, canister, pouch, bag, or other storage component, which can provide a solution for instillation therapy. Compositions of solutions may vary according to a prescribed therapy, but examples of solutions that may be suitable for some prescriptions include hypochlorite-based solutions, silver nitrate (0.5%), sulfur-based solutions, biguanides, cationic solutions, and isotonic solutions. Examples of such other therapeutic solutions that may be suitable for some prescriptions include hypochlorite-based solutions, silver nitrate (0.5%), sulfur-based solutions, biguanides, cationic solutions, and isotonic solutions. In one illustrative embodiment, the solution source 114 may include a storage component for the solution and a separate cassette for holding the storage component and delivering the solution to the tissue site 150, such as a V.A.C. VeraLink™ Cassette available from Kinetic Concepts, Inc. of San Antonio, Texas.

The container 112 may also be representative of a container, canister, pouch, or other storage component, which can be used to collect and manage exudates and other fluids withdrawn from a tissue site. In many environments, a rigid container such as, for example, a container 112, may be preferred or required for collecting, storing, and disposing of fluids. In other environments, fluids may be properly disposed of without rigid container storage, and a re-usable container could reduce waste and costs associated with negative-pressure therapy. In some embodiments, the container 112 may comprise a canister having a collection chamber, a first inlet fluidly coupled to the collection chamber and a first outlet fluidly coupled to the collection chamber and adapted to receive negative pressure from a source of negative pressure. In some embodiments, a first fluid conductor may comprise a first member such as, for example, the conduit 130 fluidly coupled between the first inlet and the tissue interface 108 by the negative-pressure interface described above, and a second member such as, for example, the conduit 126 fluidly coupled between the first outlet and a source of negative pressure whereby the first conductor is adapted to provide negative pressure within the collection chamber to the tissue site.

The therapy system 100 may also comprise a flow regulator such as, for example, a regulator 118 fluidly coupled to a source of ambient air to provide a controlled or managed flow of ambient air to the sealed therapeutic environment provided by the dressing 102 and ultimately the tissue site. In some embodiments, the regulator 118 may control the flow of ambient fluid to purge fluids and exudates from the sealed therapeutic environment. In some embodiments, the regulator 118 may be fluidly coupled by a fluid conductor or vent conduit 135 through the dressing interface 107 to the tissue interface 108. The regulator 118 may be configured to fluidly couple the tissue interface 108 to a source of ambient air as indicated by a dashed arrow. In some embodiments, the regulator 118 may be disposed within the therapy system 100 rather than being proximate to the dressing 102 so that the air flowing through the regulator 118 is less susceptible to accidental blockage during use. In such embodiments, the regulator 118 may be positioned proximate the container 112 and/or proximate a source of ambient air where the regulator 118 is less likely to be blocked during usage.

In operation, the tissue interface 108 may be placed within, over, on, or otherwise proximate a tissue site, such as tissue site 150. The cover 106 may be placed over the tissue interface 108 and sealed to an attachment surface near the tissue site 150. For example, the cover 106 may be sealed to undamaged epidermis peripheral to a tissue site. Thus, the dressing 102 can provide a sealed therapeutic environment proximate to a tissue site, substantially isolated from the external environment, and the negative-pressure source 104 can reduce the pressure in the sealed therapeutic environment. Negative pressure applied across the tissue site through the tissue interface 108 in the sealed therapeutic environment can induce macrostrain and microstrain in the tissue site, as well as remove exudates and other fluids from the tissue site, which can be collected in container 112.

In one embodiment, the controller 110 may receive and process data, such as data related to the pressure distributed to the tissue interface 108 from the pressure sensor 120. The controller 110 may also control the operation of one or more components of therapy system 100 to manage the pressure distributed to the tissue interface 108 for application to the wound at the tissue site 150, which may also be referred to as the wound pressure (WP). In one embodiment, controller 110 may include an input for receiving a desired target pressure (TP) set by a clinician or other user and may be program for processing data relating to the setting and inputting of the target pressure (TP) to be applied to the tissue site 150. In one example embodiment, the target pressure (TP) may be a fixed pressure value determined by a user/caregiver as the reduced pressure target desired for therapy at the tissue site 150 and then provided as input to the controller 110. The user may be a nurse or a doctor or other approved clinician who prescribes the desired negative pressure to which the tissue site 150 should be applied. The desired negative pressure may vary from tissue site to tissue site based on the type of tissue forming the tissue site 150, the type of injury or wound (if any), the medical condition of the patient, and the preference of the attending physician. After selecting the desired target pressure (TP), the negative-pressure source 104 is controlled to achieve the target pressure (TP) desired for application to the tissue site 150.

FIG. 2 is a schematic diagram of an example embodiment of the therapy system 100, showing some further detail and additional features, including further detail with respect to a therapy unit 201. For example, one or more components of the therapy system 100 may be packaged as a single, integrated unit, such as therapy unit 201 include, for example, the negative-pressure source 104, the controller 110, and positive pressure source 116. The therapy unit 201 may be, for example, a V.A.C. ULTA™ Therapy Unit available from Kinetic Concepts, Inc. of San Antonio, Texas. The therapy unit 201 may also include a display unit 203, which may be a graphical user interface (GUI) configured to both display data as well as receive input from a user. The therapy unit 201 further comprise one or more diagnostic modules disposed in the distribution system of the therapy system 100 such as, for example, diagnostic module 210 associated with the tissue site 150 and diagnostic module 220 associated with the negative pressure conduit 130. In some embodiments, the diagnostic module 210 may be disposed within the dressing interface 107 (as shown more specifically in FIG. 4 ) or at locations adjacent the tissue interface 108 such as between the tissue interface 108 and the cover 106 as shown in FIG. 2 or the tissue interface 108 and the tissue site 150. The therapy unit 201 may further comprise a diagnostic module 230 associated with the instillation fluid provided by the solution source 114 through the conduit 139 to the second dressing interface 117. The display unit 203 may be configured to display data related to all of the diagnostic modules. The display unit 203 may also be configured to display information related to the delivery of negative-pressure therapy and/or fluid instillation therapy to a tissue site 150. The therapy unit 201 may also include a communications device, which may be associated with the controller 110 and the display unit 203. For example, the therapy unit 201 may include a communications device 205, which may be configured to exchange data with the diagnostic modules. The communications device 205 may be a wireless device that exchanges data with communications modules associated with each of the diagnostic modules, for example, communication modules 213, 223, and 233, respectively. The communication modules may then communicate the data to the controller 110 for processing and closed-loop control of the therapy system 100 for applying negative pressure and instillation fluid to the tissue site 150. The communications device 205 may be configured to receive data and/or instructions from the controller 110 and transmit the data to the communications modules of the diagnostic modules.

Still referring primarily to FIG. 2 , the therapy system 100 may further include additional sources of solution or treatment compounds or substances, in addition to the solution source 114. For example, the therapy system 100 may include a first treatment source 260 and a second treatment source 262, both of which may be in fluid connection with the solution source 114. Each of the first treatment source 260 and the second treatment source 262 may include one or more compounds that may be delivered to the tissue site for therapeutic purposes. The first treatment source 260 and the second treatment source 262 may be arranged as part of the therapy system 100 so as to be able to modify a standard instillation solution provided by the solution source 114 by dosing with one or more additional compounds. As shown in FIG. 2 , the first treatment source 260 may be fluidly connected by first source conduit 264 to the fluid conduit 139 that connects the solution source 114 to dressing 102 via the second dressing interface 117. Similarly, the second treatment source 262 may also be fluidly connected by second source conduit 266 to fluid conduit 139.

Thus, in operation, as instillation fluid is being conducted from the solution source 114 to the dressing 102 through fluid conduit 139, additional therapeutic compounds from either or both of the first treatment source 260 and the second treatment source 262 may be conducted through first source conduit 264 and second source conduit 266, respectively, and added to the instillation fluid. Some example embodiments, the first source conduit 264 and the second source conduit 266 may be alternately coupled to the fluid conduit 139 by a fluid coupling module 270 including one-way valve 271 preventing fluid flow back to the second treatment source 262 and one-way valve 272 preventing fluid flow back to the first treatment source 260. In some other example embodiments, the fluid coupling module 270 may operatively mix the instillation solutions from each of the treatment sources that can be provided to the fluid conduit 139. In some embodiments, the diagnostic module 230 can be fluidly coupled to the fluid coupling module 274 evaluating the characteristics of the instillation solution being provided to the tissue site 150 through the second dressing interface 117 and the tissue interface 108. Additional treatment sources, such as a third treatment source and a fourth treatment source (not shown), may also be included in the therapy system 100, which may include additional treatment compounds for delivering to the tissue site.

Referring more specifically to FIG. 3A, a graph illustrating an illustrative embodiment of pressure control modes 300 that may be used for the negative-pressure and instillation therapy system of FIG. 1 is shown wherein the x-axis represents time in minutes (min) and/or seconds (sec) and the y-axis represents pressure generated by a pump in Ton (mmHg) that varies with time in a continuous pressure mode and an intermittent pressure mode that may be used for applying negative pressure in the therapy system. The target pressure (TP) may be set by the user in a continuous pressure mode as indicated by solid line 301 and dotted line 302 wherein the wound pressure (WP) is applied to the tissue site 150 until the user deactivates the negative-pressure source 104. The target pressure (TP) may also be set by the user in an intermittent pressure mode as indicated by solid lines 301, 303 and 305 wherein the wound pressure (WP) is cycled between the target pressure (TP) and atmospheric pressure. For example, the target pressure (TP) may be set by the user at a value of 125 mmHg for a specified period of time (e.g., 5 min) followed by the therapy being turned off for a specified period of time (e.g., 2 min) as indicated by the gap between the solid lines 303 and 305 by venting the tissue site 150 to the atmosphere, and then repeating the cycle by turning the therapy back on as indicated by solid line 305 which consequently forms a square wave pattern between the target pressure (TP) level and atmospheric pressure. In some embodiments, the ratio of the “on-time” to the “off-time” or the total “cycle time” may be referred to as a pump duty cycle (PD).

In some example embodiments, the decrease in the wound pressure (WP) at the tissue site 150 from ambient pressure to the target pressure (TP) is not instantaneous, but rather gradual depending on the type of therapy equipment and dressing being used for the particular therapy treatment. For example, the negative-pressure source 104 and the dressing 102 may have an initial rise time as indicated by the dashed line 307 that may vary depending on the type of dressing and therapy equipment being used. For example, the initial rise time for one therapy system may be in the range between about 20-30 mmHg/second or, more specifically, equal to about 25 mmHg/second, and in the range between about 5-10 mmHg/second for another therapy system. When the therapy system 100 is operating in the intermittent mode, the repeating rise time as indicated by the solid line 305 may be a value substantially equal to the initial rise time as indicated by the dashed line 307.

The target pressure may also be a variable target pressure (VTP) controlled or determined by controller 110 that varies in a dynamic pressure mode. For example, the variable target pressure (VTP) may vary between a maximum and minimum pressure value that may be set as an input determined by a user as the range of negative pressures desired for therapy at the tissue site 150. The variable target pressure (VTP) may also be processed and controlled by controller 110 that varies the target pressure (TP) according to a predetermined waveform such as, for example, a sine waveform or a saw-tooth waveform or a triangular waveform, that may be set as an input by a user as the predetermined or time-varying reduced pressures desired for therapy at the tissue site 150.

Referring more specifically to FIG. 3B, a graph illustrating an illustrative embodiment of another pressure control mode for the negative-pressure and instillation therapy system of FIG. 1 is shown wherein the x-axis represents time in minutes (min) and/or seconds (sec) and the y-axis represents pressure generated by a pump in Ton (mmHg) that varies with time in a dynamic pressure mode that may be used for applying negative pressure in the therapy system. For example, the variable target pressure (VTP) may be a reduced pressure that provides an effective treatment by applying reduced pressure to tissue site 150 in the form of a triangular waveform varying between a minimum and maximum pressure of 50-125 mmHg with a rise time 312 set at a rate of +25 mmHg/min. and a descent time 311 set at −25 mmHg/min, respectively. In another embodiment of the therapy system 100, the variable target pressure (VTP) may be a reduced pressure that applies reduced pressure to tissue site 150 in the form of a triangular waveform varying between 25-125 mmHg with a rise time 312 set at a rate of +30 mmHg/min and a descent time 311 set at −30 mmHg/min. Again, the type of system and tissue site determines the type of reduced pressure therapy to be used.

FIG. 3C is a flow chart illustrating an illustrative embodiment of a therapy method 320 that may be used for providing negative-pressure and instillation therapy for delivering an antimicrobial solution or other treatment solution to a dressing at a tissue site. In one embodiment, the controller 110 receives and processes data, such as data related to fluids provided to the tissue interface. Such data may include the type of instillation solution prescribed by a clinician, the volume of fluid or solution to be instilled to the tissue site (“fill volume”), and the amount of time needed to soak the tissue interface (“soak time”) before applying a negative pressure to the tissue site. The fill volume may be, for example, between 10 and 500 mL, and the soak time may be between one second to 30 minutes. The controller 110 may also control the operation of one or more components of the therapy system 100 to manage the fluids distributed from the solution source 114 for instillation to the tissue site 150 for application to the wound as described in more detail above. In one embodiment, fluid may be instilled to the tissue site 150 by applying a negative pressure from the negative-pressure source 104 to reduce the pressure at the tissue site 150 to draw the instillation fluid into the dressing 102 as indicated at 322. In another embodiment, fluid may be instilled to the tissue site 150 by applying a positive pressure from the negative-pressure source 104 (not shown) or the instillation pump 116 to force the instillation fluid from the solution source 114 to the tissue interface 108 as indicated at 324. In yet another embodiment, fluid may be instilled to the tissue site 150 by elevating the solution source 114 to height sufficient to force the instillation fluid into the tissue interface 108 by the force of gravity as indicated at 326. Thus, the therapy method 320 includes instilling fluid into the tissue interface 108 by either drawing or forcing the fluid into the tissue interface 108 as indicated at 330.

The therapy method 320 may control the fluid dynamics of applying the fluid solution to the tissue interface 108 at 332 by providing a continuous flow of fluid at 334 or an intermittent flow of fluid for soaking the tissue interface 108 at 336. The therapy method 320 may include the application of negative pressure to the tissue interface 108 to provide either the continuous flow or intermittent soaking flow of fluid at 340. The application of negative pressure may be implemented to provide a continuous pressure mode of operation at 342 as described above to achieve a continuous flow rate of instillation fluid through the tissue interface 108 or a dynamic pressure mode of operation at 344 as described above to vary the flow rate of instillation fluid through the tissue interface 108. Alternatively, the application of negative pressure may be implemented to provide an intermittent mode of operation at 346 as described above to allow instillation fluid to soak into the tissue interface 108 as described above. In the intermittent mode, a specific fill volume and the soak time may be provided depending, for example, on the type of wound being treated and the type of dressing 102 being utilized to treat the wound. After or during instillation of fluid into the tissue interface 108 has been completed, the therapy method 320 may begin may be utilized using any one of the three modes of operation at 350 as described above. The controller 110 may be utilized to select any one of these three modes of operation and the duration of the negative pressure therapy as described above before commencing another instillation cycle at 360 by instilling more fluid at 330.

As discussed above, the tissue site 150 may include, without limitation, any irregularity with a tissue, such as an open wound, surgical incision, or diseased tissue. The therapy system 100 is presented in the context of a tissue site that includes a wound that may extend through the epidermis and the dermis, and may reach into the hypodermis or subcutaneous tissue. The therapy system 100 may be used to treat a wound of any depth, as well as many different types of wounds including open wounds, incisions, or other tissue sites. The tissue site 150 may be the bodily tissue of any human, animal, or other organism, including bone tissue, adipose tissue, muscle tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, ligaments, or any other tissue. Treatment of the tissue site 150 may include removal of fluids originating from the tissue site 150, such as exudates or ascites, or fluids instilled into the dressing to cleanse or treat the tissue site 150, such as antimicrobial solutions.

As indicated above, the therapy system 100 may be packaged as a single, integrated unit such as a therapy system including all of the components shown in FIG. 1 that are fluidly coupled to the dressing 102. In some embodiments, an integrated therapy unit may include the negative-pressure source 104, the controller 110, the pressure sensor 120, and the container 112 which may be fluidly coupled to the dressing interface 107. In this therapy unit, the negative-pressure source 104 is indirectly coupled to the dressing interface 107 through the container 112 by conduit 126 and conduit 130, and the pressure sensor 120 is indirectly coupled to the dressing interface 107 by conduit 121 and conduit 122 as described above. In some embodiments, the negative pressure conduit 130 and the pressure sensing conduit 122 may be combined in a single fluid conductor 128 that can be, for example, a multi-lumen tubing comprising a central primary lumen that functions as the negative pressure conduit 130 for delivering negative pressure to the dressing interface 107 and several peripheral auxiliary lumens that function as the pressure sensing conduit 122 for sensing the pressure that the dressing interface 107 delivers to the tissue interface 108. In this type of therapy unit wherein the pressure sensor 120 is removed from and indirectly coupled to the dressing interface 107, the negative pressure measured by the pressure sensor 120 may be different from the wound pressure (WP) actually being applied to the tissue site 150. Such pressure differences must be approximated in order to adjust the negative-pressure source 104 to deliver the pump pressure (PP) necessary to provide the desired or target pressure (TP) to the tissue interface 108. Moreover, such pressure differences and predictability may be exacerbated by viscous fluids such as exudates being produced by the tissue site or utilizing a single therapy device including a pressure sensor to deliver negative pressure to multiple tissue sites on a single patient.

In some embodiments, the diagnostic modules 210, 220, 230 may include sensor devices 215, 225, and 235, respectively, which may be configured to measure one or more parameters of fluids in the fluid distribution system of the therapy system 100 that provides fluids to, and removes fluids from, the tissue site 150. The sensor devices 215, 225, and 235 may each have a sensing portion associated with the fluids and a variety of electrical devices electrically coupled to the sensing portions. The electrical devices may be electrically coupled to the communications modules 213, 223 and 233 and be referred to collectively as a sensor assembly described in more detail below. The parameters measured by the sensor device 142 may be in addition to pressure measurements gathered by one or more pressure sensors of the therapy system 100. For example, the sensor devices 215, 225, and 235 may be configured to detect and/or measure pH of fluids associated with the tissue site 150, the pH of wound exudates collected by the canister 112, and the pH of instillation fluids, respectively. The sensor devices may be configured further to detect temperature at the tissue site 150 as well as within the dressing 102, oxygen concentration of tissue at the tissue site 150 as well as in the surrounding tissue, humidity within the dressing 102, glucose levels within wound exudates, as well as other parameters. Thus, in some embodiments, the sensor devices may include one or more sensors, such as a pH sensor, temperature sensor, humidity sensor, blood sensor, glucose sensor, growth factor sensor, volatile organic compound (VOC) sensor, or another type of sensor. The sensor devices may also include a pressure sensor. Additionally, the sensor devices may include one or more sensors for detecting and/or measuring various electrolyte levels at a tissue site 150 through electrical resistance sensing.

As previously indicated, the diagnostic modules 210, 220, 230 may also include a communications component, e.g., communications modules 213, 223 and 233, for transmitting and receiving data to/from one or more other components of the therapy system 100, such as the therapy unit 201 or controller 110. For example, the communications modules may include a transceiver configured to exchange data with the communications device 205 that is part of the controller 110 or therapy unit 201. The communications modules may be configured to transmit data regarding the parameters detected and/or measured by the sensor devices 215, 225, and 235 of the diagnostic modules. In some embodiments, the communications modules 213, 223 and 233 of the diagnostic modules may be configured to wirelessly exchange data with a communications device 205 that is electrically coupled to the controller 110. For example, the communications modules 213, 223 and 233 of the diagnostic modules and the communications device 205 of the controller 110 may be configured to communicate using the Bluetooth® 4.0 protocol. Alternative wireless communication protocols may also be employed, including other Bluetooth® standards, Zigbee®, ANT, Z-WAVE, Wireless USB, or others. Other forms of wireless communication may also be incorporated, such as non-radio frequency technologies such as IrDA and Ultrasonic communications.

In some example embodiments, the diagnostic module 210 may be disposed within the dressing interface 107 which may comprise a housing having a therapy cavity that opens to the tissue site when positioned thereon. The sensing device 215 of the diagnostic module 210 may have a sensing portion disposed within therapy cavity of the dressing interface 107 including, for example, a pressure sensor, a temperature sensor, a humidity sensor, and a pH sensor. The sensors may be electrically coupled to the controller 110 outside the therapy cavity to provide data indicative of the pressure, temperature, humidity, and acidity properties within the therapeutic space of the therapy cavity. The sensors may be electrically coupled to the controller 110, for example, by the communication module 213 which may include wireless means as described generally above. In some example embodiments, the diagnostic modules 220 and 230 that are disposed at other locations as described above may also comprise a housing having a therapy or fluid cavity that opens to a space containing the wound fluids and installation fluids, respectively, as also described above. Such embodiments of the diagnostic modules 220 and 230 may also have a sensing portion disposed within the fluid cavity and include a pressure sensor, a temperature sensor, a humidity sensor, and a pH sensor that also may be electrically coupled to the controller 110. However, the diagnostic module 210 including its communication module 213 and sensing device 215 are described in more detail and may be exemplary of the other diagnostic modules 220 and 230.

The diagnostic module 210 including its communication module 213 and sensing device 215 is described in conjunction with another embodiment of a dressing interface as shown more specifically in FIGS. 4, 5A, 5B, 5C, 6A, 6B, and 7 , i.e., dressing interface 400. The dressing interface 400 is shown along with a cover or drape 406, and a tissue interface or manifold 408 disposed adjacent a tissue site 410, all of which may be functionally similar in part to the dressing interface 107, the cover 106, and the tissue interface 108, respectively, as described above. In one example embodiment, the dressing interface 400 may comprise a housing 401 and a wall 402 disposed within the housing 401 wherein the wall 402 forms a recessed space or a therapy cavity 403 that opens to the manifold 408 when disposed at the tissue site 410 and a component cavity 404 opening away from the tissue site 410 of the upper portion of the dressing interface 400. In some embodiments, sensing portions of various sensors may be disposed within the therapy cavity 403, and electrical devices associated with the sensors may be disposed within the component cavity 404 and electrically coupled to the sensing portions through the wall 402. Electrical devices disposed within the component cavity 404 may include components associated with some example embodiments of the therapy system of FIG. 1 . Although the dressing interface 400 and the therapy cavity 403 are functionally similar to the dressing interface 107 as described above, the dressing interface 400 further comprises the wall 402, the sensors, and the associated electrical devices described below in more detail. In some embodiments, the housing 401 may further comprise a neck portion or neck 407 fluidly coupled to a conduit 405. In some embodiments, the housing 401 may further comprise a flange portion or flange 409 having flow channels (see FIG. 8 ) configured to be fluidly coupled to the therapy cavity 403 when disposed on the manifold 408.

In some example embodiments, the neck 407 of the housing 401 may include portions of both the therapy cavity 403 and the component cavity 404. That portion of the neck 407 extending into the therapy cavity 403 is fluidly coupled to the conduit 405, while the portion extending into the component cavity 404 may contain some of the electrical devices. In some example embodiments, the conduit 405 may comprise a primary lumen 430 and auxiliary lumens 435 fluidly coupled by the neck 407 of the housing 401 to the therapy cavity 403. The primary lumen 430 is similar to the negative pressure conduit 130 that may be coupled indirectly to the negative-pressure source 104. The auxiliary lumens 435 are collectively similar to the vent conduit 135 that may be fluidly coupled to the regulator 118 for purging fluids from the therapy cavity 403.

In some embodiments, the component cavity 404 containing the electrical devices may be open to the ambient environment such that the electrical devices are exposed to the ambient environment. In other example embodiments, the component cavity 404 may be closed by a cover such as, for example, a cap 411 to protect the electrical devices. In still other embodiments, the component cavity 404 covered by the cap 411 may still be vented to the ambient environment to provide cooling to the electrical devices and a source of ambient pressure for a pressure sensor disposed in the therapy cavity 403 as described in more detail below. The first dressing may further comprise a drape ring 413 covering the circumference of the flange 409 and the adjacent portion of the drape 406 to seal the therapy cavity 403 of the housing 401 over the manifold 408 and the tissue site 410. In some embodiments, the drape ring 413 may comprise a polyurethane film including and an attachment device such as, for example, an acrylic, polyurethane gel, silicone, or hybrid combination of the foregoing adhesives (not shown) to attach the drape ring 413 to the flange 409 and the drape 406. The attachment device of drape ring 413 may be a single element of silicon or hydrocolloid with the adhesive on each side that functions as a gasket between the drape 406 and the flange 409. In some embodiments, the drape ring 413 may be similar to the cover 106 and/or the attachment device described above in more detail.

In some embodiments, a pressure sensor 416, a temperature and humidity sensor 418, and a pH sensor 420 (collectively referred to below as “the sensors”) may be disposed in the housing 401 with each one having a sensing portion extending into the therapy cavity 403 of the housing 401 and associated electronics disposed within the component cavity 404. The housing 401 may include other types of sensors, or combinations of the foregoing sensors, such as, for example, oxygen sensors. In some example embodiments, the sensors may be coupled to or mounted on the wall 402 and electrically coupled to electrical components and circuits disposed within the component cavity 404 by electrical conductors extending through the wall 402. In some preferred embodiments, the electrical conductors extend through pathways in the wall 402 while keeping the therapy cavity 403 electrically and pneumatically isolated from the component cavity 404. For example, the wall 402 may comprise a circuit board 432 on which the electrical circuits and/or components may be printed or mounted. In some other examples, the circuit board 432 may be the wall 402 that covers an opening between the therapy cavity 403 and the component cavity 404, and pneumatically seals the therapy cavity 403 from the component cavity 404 when seated over the opening.

In some embodiments, the electrical circuits and/or components associated with the sensors that are mounted on the circuit board 432 within the component cavity 404 may be electrically coupled to the controller 110 to interface with the rest of the therapy system 100 as described above. In some embodiments, for example, the electrical circuits and/or components may be electrically coupled to the controller 110 by a conductor that may be a component of the conduit 405. In some other preferred embodiments, a communications module 422 may be disposed in the component cavity 404 of the housing 401 and mounted on the circuit board 432 within the component cavity 404. Using a wireless communications module 422 has the advantage of eliminating an electrical conductor between the dressing interface 400 and the integrated portion of the therapy system 100 that may become entangled with the conduit 405 when in use during therapy treatments. For example, the electrical circuits and/or components associated with the sensors along with the terminal portion of the sensors may be electrically coupled to the controller 110 by wireless means such as an integrated device implementing Bluetooth® Low Energy wireless technology. More specifically, the communications module 422 may be a Bluetooth® Low Energy system-on-chip that includes a microprocessor (an example of the microprocessors referred to hereinafter) such as the nRF51822 chip available from Nordic Semiconductor. The wireless communications module 422 may be implemented with other wireless technologies suitable for use in the medical environment.

In some embodiments, a voltage regulator 423 for signal conditioning and a power source 424 may be disposed within the component cavity 404 of the housing 401, mounted on the circuit board 432. The power supply 424 may be secured to the circuit board 432 by a bracket 426. The power source 424 may be, for example, a battery that may be a coin battery having a low-profile that provides a 3-volt source for the communications module 422 and the other electronic components within the component cavity 404 associated with the sensors. In some example embodiments, the sensors, the electrical circuits and/or components associated with the sensors, the wall 402 and/or the circuit board 432, the communications module 422, and the power source 424 may be integrated into a single package and referred to hereinafter as a sensor assembly 425 as shown in FIG. 6B. In some preferred embodiments, the wall 402 of the sensor assembly 425 may be the circuit board 432 itself as described above that provides a seal between tissue site 410 and the atmosphere when positioned over the opening between the therapy cavity 403 and the component cavity 404 of the housing 401 and functions as the wall 402 within the housing 401 that forms the therapy cavity 403.

Referring now to FIGS. 8A and 8B, a perspective view and a bottom view, respectively, of a bottom surface of the flange 409 facing the manifold 408 is shown. In some embodiments, the bottom surface may comprise features or channels to direct the flow of liquids and/or exudates away from the sensors out of the therapy cavity 403 into the primary lumen 430 when negative pressure is being applied to the therapy cavity 403. In some embodiments, these channels may be molded into the bottom surface of the flange 409 to form a plurality of serrated guide channels 437, perimeter collection channels 438, and intermediate collection channels 439. The serrated guide channels 437 may be positioned and oriented in groups on bottom surface to directly capture and channel at least half of the liquids being drawn into the therapy cavity 403 with the groups of serrated guide channels 437, and indirectly channel a major portion of the balance of the liquids being drawn into the therapy cavity 403 between the groups of serrated guide channels 437. In addition, perimeter collection channels 438 and intermediate collection channels 439 redirect the flow of liquids that are being drawn in between the groups of radially-oriented serrated guide channels 437 into the guide channels 437. An example of this redirected flow is illustrated by bolded flow arrows 436. In some example embodiments, a portion of the housing 401 within the therapy cavity 403 may comprise a second set of serrated guide channels 427 spaced apart and radially-oriented to funnel liquids being drawn into the therapy cavity 403 from the flange 409 into the primary lumen 430. In other example embodiments of the bottom surface of the flange 409 and that portion of the housing 401 within the therapy cavity 403, the channels may be arranged in different patterns.

As indicated above, the sensor assembly 425 may comprise a pressure sensor 416, a humidity sensor 418, a temperature sensor as a component of either the pressure sensor 416 or the humidity sensor 418, and a pH sensor 420. Each of the sensors may comprise a sensing portion extending into the therapy cavity 403 of the housing 401 and a terminal portion electrically coupled to the electrical circuits and/or components within the component cavity 404. Referring more specifically to FIGS. 4, 6A, 6B, and 7A-7D, the housing 401 may comprise a sensor bracket 441 that may be a molded portion of the housing 401 within the therapy cavity 403 in some embodiments. The sensor bracket 441 may be structured to house and secure the pressure sensor 416 on the circuit board 432 within the therapy cavity 403 of the sensor assembly 425 that provides a seal between tissue site 410 and the atmosphere as described above. In some embodiments, the pressure sensor 416 may be a differential gauge comprising a sensing portion 442 and a terminal portion or vent 443. The vent 443 of the pressure sensor 416 may be fluidly coupled through the circuit board 432 to the component cavity 404 and the atmosphere by a vent hole 444 extending through the circuit board 432. Because the component cavity 404 is vented to the ambient environment, the vent 443 of the pressure sensor 416 is able to measure the wound pressure (WP) with reference to the ambient pressure. The sensing portion 442 of the pressure sensor 416 may be positioned in close proximity to the manifold 408 to optimize fluid coupling and accurately measure the wound pressure (WP) at the tissue site 410. In some embodiments, the pressure sensor 416 may be a piezo-resistive pressure sensor having a pressure sensing element covered by a dielectric gel such as, for example, a Model 1620 pressure sensor available from TE Connectivity. The dielectric gel provides electrical and fluid isolation from the blood and wound exudates in order to protect the sensing element from corrosion or other degradation. This allows the pressure sensor 416 to measure the wound pressure (WP) directly within the therapy cavity 403 of the housing 401 proximate to the manifold 408 as opposed to measuring the wound pressure (WP) from a remote location. In some embodiments, the pressure sensor 416 may be a gauge that measures the absolute pressure that does not need to be vented.

In some embodiments, the pressure sensor 416 also may comprise a temperature sensor for measuring the temperature at the tissue site 410. In other embodiments, the humidity sensor 418 may comprise a temperature sensor for measuring the temperature at the tissue site 410. The sensor bracket 441 also may be structured to support the humidity sensor 418 on the circuit board 432 of the sensor assembly 425. In some embodiments, the humidity sensor 418 may comprise a sensing portion that is electrically coupled through the circuit board 432 to a microprocessor mounted on the other side of the circuit board 432 within the component cavity 404. The sensing portion of the humidity sensor 418 may be fluidly coupled to the space within the therapy cavity 403 that includes a fluid pathway 445 extending from the therapy cavity 403 into the primary lumen 430 of the conduit 405 as indicated by the bold arrow to sense both the humidity and the temperature. The sensing portion of the humidity sensor 418 may be positioned within the fluid pathway 445 to limit direct contact with bodily fluids being drawn into the primary lumen 430 from the tissue site 410. In some embodiments, the space within the therapy cavity 403 adjacent the sensing portion of the humidity sensor 418 may be purged by venting that space through the auxiliary lumens 435 as described in more detail below. As indicated above, the humidity sensor 418 may further comprise a temperature sensor (not shown) as the location within the fluid pathway 445 is well-suited to achieve accurate readings of the temperature of the fluids. In some embodiments, the humidity sensor 418 that comprises a temperature sensor may be a single integrated device such as, for example, Model HTU28 humidity sensor also available from TE Connectivity.

Referring now to FIGS. 9A and 9B, the pH sensor 420 may comprise a sensing portion disposed within the therapy cavity 403 that is electrically coupled through the circuit board 432 to a front-end amplifier 421 mounted on the other side of the circuit board 432 within the component cavity 404. The front-end amplifier 421 comprises analog signal conditioning circuitry that includes sensitive analog amplifiers such as, for example, operational amplifiers, filters, and application-specific integrated circuits. The front-end amplifier 421 measures minute voltage potential changes provided by the sensing portions to provide an output signal indicative of the pH of the fluids. The sensing portion of the pH sensor 420 may be fluidly coupled to the space within the therapy cavity 403 by being positioned in the fluid pathway 445 that extends into the primary lumen 430 as described above to sense the pH changes. The sensing portion of the pH sensor 420 may be formed and positioned within the fluid pathway 445 so that the sensing portion directly contacts the wound fluid without contacting the wound itself so that the sensing portion of the pH sensor 420 does not interfere with the wound healing process. In some embodiments, the space within the therapy cavity 403 adjacent the sensing portion of the pH sensor 420 also may be purged by venting that space through the auxiliary lumens 435 as described in more detail below. In some embodiments, the pH sensor 420 may be, for example, pH sensor 450 shown in FIG. 9A that comprises a pair of printed medical electrodes including a working electrode 451 and a reference electrode 452. In some embodiments, the working electrode 451 may have a node being substantially circular in shape at one end and having a terminal portion at the other end, and the reference electrode 452 may have a node being substantially semicircular in shape and disposed around the node of the working electrode 451.

In some example embodiments, the working electrode 451 may comprise a material selected from a group including graphene oxide ink, conductive carbon, carbon nanotube inks, silver, nano-silver, silver chloride ink, gold, nano-gold, gold-based ink, metal oxides, conductive polymers, or a combination thereof. This working electrode 451 further comprise a coating or film applied over the material wherein such coating or film may be selected from a group including metal oxides such as, for example, tungsten, platinum, iridium, ruthenium, and antimony oxides, or a group of conductive polymers such as polyaniline and others so that the conductivity of the working electrode 451 changes based on changes in hydrogen ion concentration of the fluids being measured or sampled. In some example embodiments, the reference electrode 452 may comprise a material selected from a group including silver, nano-silver, silver chloride ink, or a combination thereof. The pH sensor 450 may further comprise a coating 453 covering the electrodes that insulates and isolates the working electrode 451 from the reference electrode 452 and the wound fluid, except for an electrical coupling space 454 between the nodes of the working electrode 451 and the reference electrode 452. The coating 453 does not cover the terminal portions of the working electrode 451 and the reference electrode 452 to form terminals 455 and 456, respectively, adapted to be electrically coupled to the front-end amplifier 421.

In some example embodiments, the terminal portion of the working electrode 451 and the reference electrode 452 may extend through the circuit board 432 and electrically coupled to the front-end amplifier 421 of the pH sensor 450. As indicated above, the front-end amplifier 421 of the pH sensor 450 measures minute potential changes between the working electrode 451 and the reference electrode 452 that result from a change in hydrogen ion concentration of the wound fluid as the pH of the wound fluid changes. The front-end amplifier 421 may be, for example, an extremely accurate voltmeter that measures the voltage potential between the working electrode 451 and the reference electrode 452. The front-end amplifier 421 may be for example a high impedance analog front-end (AFE) device such as the LMP7721 and LMP91200 chips that are available from manufacturers such as Texas Instruments or the AD7793 and AD8603 chips that are available from manufacturers such as Analog Devices.

In some other embodiments, the pH sensor 420 may include a third electrode such as, for example, pH sensor 460 shown in FIG. 9B that comprises a third electrode or a counter electrode 462 in addition to the working electrode 451 and the reference electrode 452 of the pH sensor 450. The counter electrode 462 also comprises a node partially surrounding the node of the working electrode 451 and a terminal 466 adapted to be electrically coupled to the front-end amplifier 421. Otherwise, the pH sensor 460 is substantially similar to the pH sensor 450 described above as indicated by the reference numerals. The counter electrode 462 is also separated from the working electrode 451 and is also insulated from the wound fluid and the other electrodes by the coating 453 except in the electrical conductive space 454. The counter electrode 462 may be used in connection with the working electrode 451 and the reference electrode 452 for the purpose of error correction of the voltages being measured. For example, the counter electrode 462 may possess the same voltage potential as the potential of the working electrode 451 except with an opposite sign so that any electrochemical process affecting the working electrode 451 will be accompanied by an opposite electrochemical process on the counter electrode 462. Although voltage measurements are still being taken between the working electrode 451 and the reference electrode 452 by the analog front-end device of the pH sensor 460, the counter electrode 462 may be used for such error correction and may also be used for current readings associated with the voltage measurements. Custom printed electrodes assembled in conjunction with a front-end amplifier may be used to partially comprise pH sensors such as the pH sensor 450 and the pH sensor 460 may be available from several companies such as, for example, GSI Technologies, Inc. and Dropsens.

As described above, the sensing portions of the sensors may all be disposed within the therapy cavity 403 and electrically coupled through the circuit board 432 to the front-end amplifier 421 and the communications module 422 mounted on the other side of the circuit board 432 within the component cavity 404. In some embodiments, sensor assembly 425 may comprise a processing element that may include the communications module 422 which may include the microprocessor and/or the wireless communications chip described above. The processing element may further include the front-end amplifier 421 and any other components that are disposed within the component cavity 404. The processing element may be electrically coupled to the sensing portions of the sensors for receiving property signals from the sensing portions that are indicative of the pressure, humidity, temperature, and the pH of the fluid at the tissue site in order to determine the flow characteristics of the system and the progression of wound healing as described in more detail below.

The embodiments of the therapy systems described herein overcome the problems associated with having a large head pressure in a closed pneumatic environment, and the problems associated with using a vent disposed on or adjacent the dressing interface. More specifically, the embodiments of the therapy systems described above comprise a pressure sensor, such as the pressure sensor 416, disposed within the pneumatic environment, i.e., in situ, that independently measures the wound pressure (WP) within the therapy cavity 403 of the housing 401 as described above rather than doing so remotely. Consequently, the pressure sensor 416 is able to instantaneously identify dangerously high head pressures and/or blockages within the therapy cavity 403 adjacent the manifold 408. Because the auxiliary lumens 435 are not being used for pressure sensing, the auxiliary lumens 435 may be fluidly coupled to a fluid regulator such as, for example, the regulator 118 in FIG. 1 , that may remotely vent the therapeutic environment within the therapy cavity 403 to the ambient environment or fluidly couple the therapeutic environment to a source of positive pressure. The regulator 118 may then be used to provide ambient air or positive pressure to the therapeutic environment in a controlled fashion to “purge” the therapeutic environment within both the therapy cavity 403 and the primary lumen 430 to resolve the problems identified above regarding head pressures and blockages, and to facilitate the continuation of temperature, humidity, and pH measurements as described above.

Using a regulator to purge the therapeutic environment is especially important in therapy systems such as those disclosed in FIGS. 1 and 3C that include both negative pressure therapy and instillation therapy for delivering therapeutic liquids to a tissue site. For example, in one embodiment, fluid may be instilled to the tissue site 150 by applying a negative pressure from the negative-pressure source 104 to reduce the pressure at the tissue site 150 to draw the instillation liquid into the dressing 102 as indicated at 302. In another embodiment, liquid may be instilled to the tissue site 150 by applying a positive pressure from the negative-pressure source 104 (not shown) or the instillation pump 116 to force the instillation liquid from the solution source 114 to the tissue interface 108 as indicated at 304. Such embodiments may not be sufficient to remove all the instillation liquids from the therapeutic environment, or may not be sufficient to remove the instillation liquids quickly enough from the therapeutic environment to facilitate the continuation of accurate temperature, humidity, and pH measurements. Thus, the regulator 118 may be used to provide ambient air or positive pressure to the therapeutic environment to more completely or quickly purge the therapeutic environment to obtain the desired measurements as described above.

In embodiments of therapy systems that include an air flow regulator comprising a valve such as the solenoid valve described above, the valve provides controlled airflow venting or positive pressure to the therapy cavity 403 as opposed to a constant airflow provided by a closed system or an open system including a filter in response to the wound pressure (WP) being sensed by the pressure sensor 416. The controller 110 may be programmed to periodically open the solenoid valve as described above allowing ambient air to flow into the therapy cavity 403, or applying a positive pressure into the therapy cavity 403, at a predetermined flow rate and/or for a predetermined duration of time to purge the pneumatic system including the therapy cavity 403 and the primary lumen 430 of bodily liquids and exudates so that the humidity sensor 418 and the pH sensor 420 provide more accurate readings and in a timely fashion. This feature allows the controller to activate the solenoid valve in a predetermined fashion to purge blockages and excess liquids that may develop in the fluid pathways or the therapy cavity 403 during operation. In some embodiments, the controller may be programmed to open the solenoid valve for a fixed period of time at predetermined intervals such as, for example, for five seconds every four minutes to mitigate the formation of any blockages.

In some other embodiments, the controller may be programmed to open the solenoid valve in response to a stimulus within the pneumatic system rather than, or additionally, being programmed to function on a predetermined therapy schedule. For example, if the pressure sensor is not detecting pressure decay in the canister, this may be indicative of a column of fluid forming in the fluid pathway or the presence of a blockage in the fluid pathway. Likewise, the controller may be programmed to recognize that an expected drop in canister pressure as a result of the valve opening may be an indication that the fluid pathway is open. The controller may be programmed to conduct such tests automatically and routinely during therapy so that the patient or caregiver can be forewarned of an impending blockage. The controller may also be programmed to detect a relation between the extent of the deviation in canister pressure resulting from the opening of the valve and the volume of fluid with in the fluid pathway. For example, if the pressure change within the canister is significant when measured, this could be an indication that there is a significant volume of fluid within the fluid pathway. However, if the pressure change within the canister is not significant, this could be an indication that the plenum volume was larger.

The systems, apparatuses, and methods described herein may provide other significant advantages over dressing interfaces currently available. For example, another advantage of using the dressing interface 400 that includes a pressure sensor in situ such as, for example, the pressure sensor 416, is that the pressure sensor 416 can more accurately monitor the wound pressure (WP) at the tissue site and identify blockages and fluid leaks that may occur within the therapeutic space or other distribution components of the system as described in more detail above. Another advantage of using the dressing interface 400 that includes a pressure sensor in situ is that one of the auxiliary lumens 435 are freed up to vent or actively purge the sensing portions of the sensors within the therapeutic cavity 403 so that meaningful data regarding the sensing properties can be obtained on a timely basis for providing the therapy and detecting the flow characteristics of the system and the status of wound healing. Yet another advantage of using a dressing interface including in situ sensors, e.g., the dressing interface 400, is that the sensor assembly 425 provides additional data including pressure, temperature, humidity, and pH of the fluids being drawn from the tissue site that facilitates improved control algorithms for detecting flow characteristics within the system and profiling the status of wound healing. Such improvements further assist the caregiver with additional information provided by the therapy unit of the therapy system to optimize the wound therapy being provided and the overall healing progression of the tissue site when combined with appropriate control logic.

As indicated above, the processing element of the sensor assembly 425 may receive property signals indicative of the pressure, the humidity, the temperature, and the pH within the therapy cavity 403 that may be transmitted to the controller 110 of the system for applying therapy to the tissue site and detecting the flow characteristics of the system and the status of wound healing at the tissue site. In some embodiments, the flow characteristics may include the detection of blockages, fluidly leaks, air leaks, and desiccation conditions associated with the dressing interface and the system. The property signals associated with the fluids at a specific time may be processed and logged by the controller 110 and assessed with previous property signal measurements. The controller 110 may also be programmed with a negative pressure control algorithm that assesses the logged property signals to assess the status of wound healing and with that assessment adjust the pump pressure (PP) and/or the pump duty cycle (PD) if necessary to maintain the wound pressure (WP) proximate the desired target pressure (TP).

Referring to FIG. 10 , a flowchart is shown that illustrates a method for treating a tissue site in some embodiments of therapy systems including, for example, the therapy system 100. More specifically, such method may utilize a dressing interface or sensing pad such as, for example, the dressing interface 400 of FIG. 4 , for applying negative-pressure therapy with fluid instillation therapy and sensing properties of wound exudates extracted from a tissue site as shown at 600. A tissue interface such as the tissue interface 108 may be placed within, over, on, or otherwise proximate a tissue site at 601. A cover such as the cover 106 may be placed over the tissue interface 108 and sealed to an attachment surface near the tissue site 150. For example, the cover 106 may be sealed to undamaged epidermis peripheral to a tissue site. Thus, the dressing 102 provides a sealed therapeutic environment proximate to a tissue site, substantially isolated from the external environment, while the negative-pressure source 104 reduces the pressure within the sealed therapeutic environment and the instillation pump 116 provides fluids to the sealed therapeutic environment as described above. In some embodiments, the method may further comprise applying the sensing pad or dressing interface to the tissue interface at 602. More specifically, applying the sensing pad may include positioning the housing on the dressing interface so that the aperture of the housing is in fluid communication with the tissue interface. The dressing interface may comprise a wall disposed within the housing to form a therapy cavity within the housing and a component cavity fluidly sealed from the therapy cavity, wherein the therapy cavity opens to the aperture as described above. Such dressing interface may further comprise a negative-pressure port fluidly coupled to the therapy cavity and adapted to be fluidly coupled to a negative-pressure source as described above. The dressing interface may further comprise a processing element disposed in the component cavity or outside the therapy cavity, similar to the processing element described above.

Still referring to 602, the method may further comprise connecting the sensing pad to a wound therapy device such as, for example, the therapy system 100. Connecting the sensing pad may include coupling the therapy cavity of the sensing pad to a negative-pressure source and to a vent as described above, and electrically coupling the processing element to a controller of the therapy system such as, for example, the controller 110. The sensing pad or the dressing interface may further comprise a pH sensor, a temperature sensor, a humidity sensor, and a pressure sensor, each having a sensing portion disposed within the therapy cavity and each electrically coupled to the processing element through the wall as described above.

Referring now to 603, the method may further comprise initializing therapy settings for both the negative pressure therapy and the fluid instillation therapy to be provided for treatment. The therapy settings may include, for example, the initial settings for the sensor readings of the pH sensor, the temperature sensor, the humidity sensor, and the pressure sensor that may be stored on the controller 110. The therapy settings for the negative pressure therapy phase may also include, for example, any initial values associated with the pump pressure (PP), the pump duty cycle (PD), or the desired target pressure (TP) of the negative-pressure source 104. The therapy settings for the fluid instillation therapy phase may further include any initial values associated with the fill volume and the soak time, as well as an instillation pump pressure (IP), an instillation duty cycle (ID), and a desired fluid pressure (FP) of the instillation pump 116 for the fluid instillation therapy phase of the therapy treatment.

After the therapy settings are initialized, the method may further comprise a caregiver or patient turning on the therapy system 100 to begin applying a desired therapy treatment at 604. The desired therapy treatment may include negative pressure therapy, instillation therapy, or other therapy for treating the tissue site as indicated. In some embodiments, for example, the method may comprise applying negative-pressure therapy at 605 to the therapy cavity of the dressing interface to draw fluids from the tissue interface into the therapy cavity and exiting out of the reduced-pressure port. The method may further comprise sensing the pH, temperature, humidity, and pressure properties of the fluids flowing through therapy cavity utilizing the sensing portion of the sensors which may provide property signals indicative of such properties to the processing element. Applying negative-pressure therapy may further comprise providing the property signals from the processing element to the controller of the therapy system for processing the property signals and treating the tissue site in response to the property data being collected and processed by the therapy system.

In some embodiments, the method may further comprise applying fluid instillation therapy at 606 to the therapy cavity of the dressing interface to provide fluids to the therapy cavity either directly to the therapy cavity of the dressing interface or indirectly from another location on the dressing as described above, and ultimately exiting out of the reduced-pressure port. In some embodiments, fluid instillation therapy may be provided prior to or concurrent with negative pressure therapy as described in more detail above. The method may further comprise sensing the pH, temperature, humidity, and pressure properties of the fluids flowing through therapy cavity utilizing the sensing portion of the sensors which may provide property signals indicative of such properties to the processing element. Applying fluid instillation therapy may further comprise providing the property signals from the processing element to the controller of the therapy system for processing the property signals and treating the tissue site in response to the sensor data being collected and processed by the therapy system.

Referring to decision block 607, the method may further comprise turning off the therapy treatment when receiving a signal from a caregiver, a patient, or from a control algorithm stored on the controller of the therapy system for assessing the sensor data and corresponding health of the tissue site as described in more detail below. If the therapy system is turned off (YES) ending the therapy treatment at 608, the method may further comprise removing the dressing interface, the cover, and the sensing pad at 609 after the therapy system is turned off as indicated. If no such signal is received to turn off the therapy treatment, the method in some embodiments may loop back to 605 to continue applying the negative-pressure therapy with fluid instillation to the dressing interface and the tissue site. When the method loops back to 605, the method may include commands provided by the control algorithms to continue controlling the negative pressure therapy by increasing the pump pressure (PP) or the pump duty cycle (PD) along with the fluid instillation therapy by adjusting the instillation pump pressure (IP) or the instillation duty cycle (ID).

FIG. 11 is a schematic block diagram illustrating an embodiment of a control algorithm that may comprise a negative pressure control algorithm that may be utilized when applying the negative-pressure therapy within the tissue treatment method 600, hereinafter referred to as the negative pressure control algorithm 605. The negative pressure control algorithm 605 may include the detection of dressing flow characteristics within the system and an assessment of sensor properties based on the property data stored on the controller of the therapy system. FIG. 13 shows a flow chart illustrating one embodiment of a method that may operate within the negative pressure control algorithm 605. Other exemplary embodiments of methods that may be used in conjunction with the negative pressure control algorithm 605 are scribed in co-pending U.S. Patent Application No. 62/617,521 filed on Jan. 15, 2018, which is incorporated herein by reference in its entirety. The negative pressure therapy algorithm 605 may commence by initializing the therapy settings at 603 including the sensor settings by setting initial values of the property signals provided by the sensors to the processing element of the dressing interface and ultimately to the controller of the therapy system as indicated for processing and assessment.

The negative pressure control algorithm 605 may include a wound pressure control 610 as shown in FIG. 11 that compares wound pressure (WP) to the target pressure (TP), and then provides commands to increase or decrease the pump duty cycle (PD) accordingly and/or log the sensor readings of the sensor properties at 650. Referring more specifically to FIG. 13 , if the wound pressure (WP) is greater than the target pressure (TP) at 611 (YES), the wound pressure control 610 may generate a command to vent the therapy cavity at 612 as described above and a command to reduce the pump duty cycle (PD) at 613. After the pump duty cycle (PD) is reduced, the property signals may then be logged in the controller of the therapy system as indicated at 650 for further processing by a set of assessment algorithms as indicated at 651. If the wound pressure (WP) is not greater than the target pressure (TP) at 611 (NO), the wound pressure (WP) is again compared to the target pressure (TP) at 614. If the wound pressure (WP) is not less than the target pressure (TP), i.e., greater than or equal to the target pressure (TP), the wound pressure control 610 may generate a command to maintain or reduce the pump duty cycle (PD) at 615 and the property signals may then be logged in the controller of the therapy system as indicated at 650 for further processing by the assessment algorithms 651. However, if the wound pressure (WP) is less than or equal to the target pressure (TP), the wound pressure control 610 may generate a command to increase the pump duty cycle (PD) at 616. When the pump duty cycle (PD) is increased, the negative pressure control algorithm 605 in some embodiments may proceed to dressing-alert algorithms including, for example, a blockage detection algorithm and fluid leak detection algorithm shown generally at 620 in FIG. 11 , and an air leak detection algorithm and desiccation detection algorithm shown generally at 640 in FIG. 11 . Other example embodiments of blockage detection algorithms, fluid leak detection algorithms, air leak detection algorithms and desiccation detection algorithms are described more specifically in co-pending U.S. Patent Application No. 62/617,521 filed on Jan. 15, 2018, which is incorporated herein by reference in its entirety.

In some embodiments of a therapy system such as, for example, therapy system 100, the therapy system may comprise a user interface coupled to the controller 110. Referring more specifically to FIG. 12 , a block diagram of one example embodiment of a user interface, user interface 660, that may comprise a variety of alerts and alarms associated with the dressing flow characteristics of FIG. 11 . These alerts and/or alarms associated with the dressing flow characteristics may comprise, for example, alerts and/or alarms for a blockage condition 661, a fluid leak condition 662, an air leak condition 663, or a desiccation condition 664. The negative pressure control algorithm may be programmed to generate an alarm based on the occurrence of a predetermined number of alerts such as, for example, generating alarm after the occurrence of three alerts. The user interface 660 may also provide alerts and/or alarms that may be associated with wound progress 665 and/or canister-full alert 667 based on the fluid properties being provided by the sensing pad or the dressing interface 400, for example. All of the fluid properties and associated alerts and/or alarms identified above may be selectively provided for each wound dressing (WD #1, WD #2 or WD #3) such as, for example, wound dressings substantially similar to the dressing 102, that may be fluidly and electrically coupled to the therapy system 100. For example, a patient or caregiver may select a desired wound dressing by setting a wound dressing selection switch 668. Alternatively, the controller of the therapy system may be programmed to selectively collect the fluid properties and provide alerts and/or alarms based on a predetermined order with times designated for each wound dressing.

Referring back to FIG. 11 , a new set of property signals indicative of the sensor properties may be logged at 650 into the controller of the therapy system as a result of the alerts, alarms, and other events described above with respect to the negative pressure control algorithm 605 including the wound pressure control 610, the blockage detection and fluid leak detection algorithms 620, and the air leak detection algorithm and desiccation detection algorithm at 640. Logging these property signals along with contemporaneous readings of the wound pressure (WP), the pump pressure (PP), and the pump duty cycle (PD) generates sets of property data that may include humidity data, temperature data, and pH data being provided by the processing element such as, for example, the sensor assembly 425 in addition to the pressure data, duty cycle data, and other data that might be available from other sensors in the therapy system 100. Such other sensors also may be coupled to the controller or other distribution components in the therapy system. In some embodiments, the negative pressure control algorithm 605 may be configured to assess the pH data at 652, the humidity data at 654, and the temperature data at 656, and use such data to assess the status of wound health of the tissue site at 658, and further configured to return to the wound pressure control 610 after the assessments have been completed. In some embodiments, the assessments may include an analysis of whether the data is increasing or decreasing and how rapidly the data may be increasing or decreasing. In some embodiments, the assessments may further include an analysis of whether the data may increase or decrease and how rapidly that data may fluctuate in each direction. In some embodiments, the assessment may further include a determination that the relevant data is simply not affected.

The assessments of the pH data at 652, the humidity data at 654, and the temperature data at 656 along with contemporaneous wound pressure (WP) data, pump pressure (PP) data, and the pump duty cycle (PD) data may be utilized to assess the health of the wound at 658 including, for example, the progression of wound healing, i.e., the wound status.

TABLE 1 Wound Status: Inputs Wound Health/Progression Wound Pressure Critically affected (WP) (May Increase or Decrease) Wound Humidity May increase or decrease (Hum) slowly Wound pH Will change with wound regression or progression (May Increase or Decrease) Wound Temperature May increase or decrease (Temp) slowly

Referring more specifically to Table 1, the wound status may include a determination of the progression of wound healing that may be identified by the assessment of the pH data, the humidity data, and the temperature data along with contemporaneous wound pressure (WP) data, pump pressure (PP) data, and the pump duty cycle (PD) data. For example, a wound healing state may be identified when the pH data changes in response to wound healing regression or progression. In some embodiments, the wound may be considered in a healthy state if the wound fluids have a pH of approximately 7.4+/−0.2 and the pH data indicates that the pH has held at that value over a predetermined time period. In some other embodiments, the wound may be considered in a healthy state if the wound fluids have a slightly acidic pH that stays within a range from about 4.0 to about 6.3 and remains within that range over a predetermined time period. Additionally, if the wound fluid has an alkaline pH in a range of about 7.15 to about 8.93, the wound may be considered to be in a chronic state.

The pH sensor 420 of the sensor assembly 425, as well as the sensor device 215 and the communication module 213 of the diagnostic module 210, provides pH data to the communication device 205 and the controller 110 as described above which actively monitors and controls the pH sensors to provide feedback within the therapy control algorithms (both negative pressure and instillation) in order to adjust the pH level at the tissue site. In one example embodiment, the first treatment source 260 may contain instillation fluids having a desired or target pH that is provided during a normal fluid instillation cycle as described above and the second treatment source 262 may contain instillation fluids having a corrective pH capability when the pH at the tissue site exceeds the target. For example, a target pH of 7.4+/−0.2 for the tissue site may be initialized at 603 as described above and then monitored by the pH sensor 420 or the diagnostic module 210. The pH at the tissue site may then be assessed at 652 and communicated back to the communications device 205 and the controller 110. If, for example, the pH at the tissue site is an alkaline pH of 8.0, the negative pressure control algorithm at 605 may generate a command to provide a wound progress alert at 665 and begin fluid instillation therapy at 606 by activating the second treatment source 262 to provide instillation fluids to the tissue interface 108 or 408 in order to reduce the alkaline pH of wound fluids at the tissue site back to the acceptable range. The controller 110 may be programmed to adjust the soak time and/or the dwell time of the instillation cycle until the pH of the wound fluids at the tissue site returns to an acceptable range. The controller 110 may also be programmed to optimize the soak time or the dwell time to maintain the pH of the wound fluids within the acceptable range. The pH of the wound fluid at the tissue site may be modulated by delivering instillation fluid to the tissue site that comprises, for example, phosphate buffered saline, acetic acid, soluble salts. Corrective instillation fluid may also comprise a hypochlorous solution having an acidic pH of about 2.5 to 3.0 value.

In some embodiments, the sensor device 235 and the communication module 233 of the diagnostic module 230 may also be adapted to confirm the correct instillation fluid with the desired pH is being provided to the tissue interface to ensure proper treatment of wound fluids at the tissue site. Additionally, the controller 110 may be adapted to mix the instillation fluids from the first treatment source 260 and the second treatment source 262 to adjust the pH of the instillation fluid being provided to the tissue site. The diagnostic module 230 may be further adapted to monitor the adjusted pH value of the instillation fluid and provide that value back to the controller 110 to further adjust the pH of the instillation fluid being provided to the wound fluid at the tissue site until it reaches the desired target range.

In some embodiments, the sensor device 225 and the communication module 223 of the diagnostic module 220 may be associated with the negative pressure conduit 130 as shown and be configured to sense and communicate pH data to the communications device 205 and the controller 110. In yet other embodiments, the diagnostic module 220 may be disposed to the exudate fluids flowing into and contained by the canister 112. In some embodiments it may be desirable to position the diagnostic module 220 proximate the inlet of the canister 112 to sense the pH of exudate fluids most recently removed from the tissue site. The controller 110 may be configured to compare the pH of the exudate fluids flowing into the canister 112 and sensed by the diagnostic module 220 with the pH sensed by the diagnostic module 210 at the tissue site. Such pH assessments at 652 and subsequent comparisons by the controller 110 may be further assessed to determine whether the fluid instillation therapy at 606 needs to be adjusted to maintain or correct the pH of wound fluids at the tissue site, e.g., communicating adjustments to the dwell time and/or soak time as described above. For example, if the pH of the exudate fluids sensed by the diagnostic module 220 has decreased, but the pH of the wound fluids sensed by the diagnostic module 210 at the tissue site has not decreased, the controller 110 may adjust the instillation pump 116 to increase the dwell time and/or soak cycle of the instillation fluid provided by the first and/or second treatment source 260 and/or 262, respectively, to achieve the target pH of the wound fluids. Another example of the controller's ability to make adjustments to the fluid instillation therapy at 606 occurs when the pH of the exudate fluids indicates a delayed reduction in the pH compared to the pH of the wound fluids at the tissue site. This would indicate that the installation fluids are being removed too quickly from the tissue site so that the soak time of the fluid instillation therapy should be increased and/or the duty cycle of the negative pressure therapy should be decreased so that the wound fluids are not removed too quickly. Besides providing feedback control for the pH loop as described above and further below, this control system is also capable of learning what adjustments might be necessary for a specific tissue site based on pH measurements that the controller 110 receives from the diagnostic modules 210, 220 and 230 over time. Essentially, the system is also capable of determining the rate of change of the pH measurements to determine the progress of wound healing based on adjustments to the fluid instillation therapy such as, for example, adjustments to the dwell time and soak time, and receiving an alert at 665 if progress is not sufficient.

In some embodiments, the wound healing state may be identified when the humidity data and the temperature data both increase or decrease slowly at predetermined rates. For example, if the temperature data indicates that the temperature is increasing, the increasing temperature may be an indication that the wound is infected. Additionally, the wound pressure (WP) or the pump pressure (PP) may critically affect the healing progression or regression. For example, if the pressure is not within the therapeutic range that was prescribed, then the patient is not getting the benefit of the therapy. However, wound progression or regression does not necessarily affect the wound pressure (WP) or the pump pressure (PP). In some embodiments, the negative pressure control algorithm 605 may generate a command to provide an alert 665 and continue providing therapy including, for example, the instillation of fluids that may include medication until the pH returns to an acceptable range.

FIG. 14 is a schematic block diagram illustrating an embodiment of a control algorithm that may comprise a fluid instillation control algorithm that may be utilized when applying the fluid instillation therapy 606 within the tissue treatment method 600, hereinafter referred to as the fluid instillation control algorithm 706. The fluid instillation control algorithm 706 may include the detection of dressing flow characteristics within the system and an assessment of sensor properties based on the property data stored on the controller of the therapy system. The fluid instillation therapy algorithm 706 may commence by initializing the therapy settings at 603 including logging the baseline readings of the sensors at 703 and setting the initial values of the property signals provided by the sensors. In some embodiments, the property signals may be sent to the processing element of the dressing interface and ultimately to the controller of the therapy system as indicated for processing and assessment.

A tissue interface such as the tissue interface 108 may be placed within, over, on, or otherwise proximate a tissue site as described above, and may include an accelerometer or other device for determining whether the sensors within the dressing interface are properly oriented at the tissue site. The fluid instillation control algorithm 706 may include a dressing orientation process at 708 that processes data from the accelerometer to determine whether sensors in the dressing interface are correctly oriented with respect to the tissue interface at the tissue site. If the sensors are not correctly oriented (NO), the fluid instillation control algorithm 706 in some embodiments may proceed to a dressing-fill assist subroutine at 710 shown more specifically in FIG. 15 . When the dressing-fill assist subroutine is completed, the sensor readings may be logged and assessed at 720 along with a measurement of the amount of fluid dispensed to the tissue interface, i.e., the dispensed fill volume, as a result of the dressing-fill assist subroutine. After the sensor readings and the dispensed fill volume have been logged and assessed, the fluid instillation control algorithm 706 may further comprise providing wound pressure alerts at 721 similar to those described above.

Referring back to 708, if the tissue interface is correctly oriented (YES), the fluid instillation control algorithm 706 in some embodiments may proceed to a pump control routine the compares the relative dressing humidity to a target humidity, and then provides commands to start or stop the instillation pump depending on the results of the comparison. More specifically, the pump control routine may compare the relative dressing humidity to the target humidity at 722 and stop the instillation pump at 723 (YES) if the relative dressing humidity exceeds the target humidity. After the instillation pump has been stopped at 723, the sensor readings and the dispensed fill volume may be logged and assessed at 720 and wound pressure alerts may be provided at 721. The pump control routine may include a redundant check of the role dressing humidity in comparison to the target humidity at 724 and stop the instillation pump at 725 (NO) if the relative dressing humidity is less than the target humidity. After the instillation pump has been stopped at 725, the sensor readings and the dispensed fill volume may be logged and assessed at 720 and wound pressure alerts may be provided at 721. Thus, if the relative dressing humidity is not greater than the target humidity at 722 and less than the target humidity at 724, then the fluid instillation control algorithm 706 in some embodiments may proceed to dressing-alert algorithms including, for example, a blockage detection algorithm and fluid leak detection algorithm shown generally at 730 shown more specifically in co-pending U.S. Patent Application No. 62/617,521 filed on Jan. 15, 2018, which is incorporated herein by reference in its entirety. After either a blockage or dressing leak has been identified, the fluid instillation control algorithm 706 in some embodiments may log the sensor readings at 750 and loop back to 722 for further comparisons of the relative dressing humidity to the target humidity. However, if the relative dressing humidity is greater than the target humidity at 722 and not less than the target humidity at 724, the pump may be stopped to log and assess the sensor readings and the dispensed volume.

The fluid instillation control algorithm 706 may further comprise a fill assist algorithm 710 that may facilitate determining whether the tissue interface has been instilled with a volume of fluids desired for the instillation therapy, i.e., a desired fill volume. Referring more specifically to FIG. 15 , the fill assist algorithm 710 may comprise a dead space detection algorithm 711 that may be similar to the dead space detection algorithm 743 described above. The fill assist algorithm 710 may then proceed to provide a command to a controller to evacuate a therapy cavity of a dressing interface such as, for example, the controller 110 evacuating the therapy cavity 403 of the dressing interface 400, to a negative pressure sufficient to commence instillation of the fluids at 712. For example, a negative pressure of about 25 mmHg, which is well below the negative pressure therapy level of negative pressure, may be applied to the therapy cavity to commence instillation of the fluids. The negative pressure may be provided by the suction of a negative pressure pump such as, for example, the negative pressure pump 104, as described in more detail above.

In some embodiments, providing this suction may be sufficient for instilling fluid into the therapy cavity. In other embodiments, an instillation pump such as, for example, the instillation pump 116, may be used in conjunction with the suction to commence instillation. For example, the instillation pump may provide a positive force to instill the fluids into the therapy cavity as shown at 713 and may be supplemented by continuing to provide negative pressure from the negative pressure pump. The fill assist algorithm 710 may also include a pressure check algorithm at 714 for determining whether pressure changes within the therapy cavity are within an acceptable range, while instilling fluids into the therapy cavity and allowing those fluids to soak for a desirable so time. If the pressure measured is not within the acceptable range (NO), the fill assist algorithm 710 may generate a dressing leak alarm at 741. However, if the pressure measured is within the acceptable range (YES), the fill assist algorithm 710 may provide a command to a controller to generate a command to open a pressure relief valve at 715 such as, for example, the controller 110 generating a command to the regulator 118 as described above, in order to further evacuate gases from the therapy cavity and draw liquids into the therapy cavity. The controller may be programmed to open the pressure relief valve for a fill period sufficient to provide the therapy cavity and the tissue interface with a desired fill volume. The fill assist algorithm 710 may also continue providing fill assist at 716 by refilling the therapy cavity until previous fill volumes are achieved for another cycle of instillation therapy. Whenever the desired fill volume or fill volumes are achieved, the fill assist algorithm 710 may proceed back to the fluid instillation control algorithm 706 so that the sensor readings may be logged and assessed at 720 along with a measurement of the amount of fluid dispensed to the tissue interface, i.e., the dispensed fill volume. After the sensor readings and the dispensed fill volume have been logged and assessed, the fluid instillation control algorithm 706 may continue by providing wound pressure alerts at 721 similar to those described above.

A new set of sensor readings indicative of the sensor properties and dispensed volumes may be logged at 720 into the controller of the therapy system as a result of the alerts, alarms, and other events described above with respect to the fluid instillation control algorithm 706 including the dressing orientation control 708, the fill assist algorithm 710, and the blockage detection and fluid leak detection algorithms 730. Logging these property signals along with contemporaneous readings of the wound pressure (WP), the instillation pump pressure (IP), and the instillation pump duty cycle (ID) generates sets of property data that also may include humidity data, temperature data, and pH data being provided by the processing element such as, for example, the sensor assembly 425 and the diagnostic modules 210, 220 and 230. Such other sensors also may be coupled to the controller or other distribution components in the therapy system. In some embodiments, the fluid instillation control algorithm 706 may be configured to assess the pH data, the humidity data, the temperature data, and the dispensed volume of fluids, and then use such assessment data to evaluate the status of wound health of the tissue site at 721. The fluid instillation control algorithm 706 may be configured further to return to the wound pressure control algorithm 605 after such assessments have been completed. In some embodiments, the assessments may include an analysis of whether the assessment data is increasing or decreasing and how rapidly the data may be increasing or decreasing. In some embodiments, the assessment may further include a determination that the relevant data is simply not affected.

While shown in a few illustrative embodiments, a person having ordinary skill in the art will recognize that the systems, apparatuses, and methods described herein are susceptible to various changes and modifications. For example, certain features, elements, or aspects described in the context of one example embodiment may be omitted, substituted, or combined with features, elements, and aspects of other example embodiments. Moreover, descriptions of various alternatives using terms such as “or” do not require mutual exclusivity unless clearly required by the context, and the indefinite articles “a” or “an” do not limit the subject to a single instance unless clearly required by the context. Components may be also be combined or eliminated in various configurations for purposes of sale, manufacture, assembly, or use. For example, in some configurations the dressing 102, the container 112, or both may be eliminated or separated from other components for manufacture or sale. In other example configurations, the controller 110 may also be manufactured, configured, assembled, or sold independently of other components.

The appended claims set forth novel and inventive aspects of the subject matter described above, but the claims may also encompass additional subject matter not specifically recited in detail. For example, certain features, elements, or aspects may be omitted from the claims if not necessary to distinguish the novel and inventive features from what is already known to a person having ordinary skill in the art. Features, elements, and aspects described herein may also be combined or replaced by alternative features serving the same, equivalent, or similar purpose without departing from the scope of the invention defined by the appended claims. 

What is claimed is:
 1. A system for controlling negative pressure and instillation therapy at a tissue site based on properties of wound fluids, the system comprising: a tissue interface adapted to be disposed at the tissue site and adapted to be coupled to a source of instillation fluid; and a dressing interface adapted to couple a source of negative-pressure to the tissue interface, the dressing interface comprising: a housing having a therapy cavity including an opening configured to be disposed in fluid communication with the tissue interface, and a negative-pressure port adapted to fluidly couple the therapy cavity to the source of negative-pressure; a pH sensor in fluid communication with the therapy cavity and configured to sense pH of the wound fluids; and a processing element electrically coupled to the pH sensor for receiving a property signal indicative of the pH of the wound fluids, the processing element being further configured to assess the health characteristics of the tissue site based on the pH of the wound fluids and modify the instillation therapy in response to the pH measured.
 2. The system of claim 1, wherein the pH sensor is disposed within the therapy cavity adjacent to the tissue interface.
 3. The system of claim 1, wherein the pH sensor is disposed within the therapy cavity adjacent to the tissue site.
 4. The system of claim 1, wherein the pH sensor is disposed in a conduit between the negative-pressure port and the source of negative-pressure.
 5. The system of claim 1, wherein the pH sensor is disposed in a canister between the negative-pressure port and the source of negative-pressure.
 6. The system of claim 1, wherein the processing element is further configured to modify the instillation therapy by adjusting the dwell time of instillation fluid delivered to the tissue site.
 7. The system of claim 1, wherein the processing element is further configured to modify the instillation therapy by adjusting the soak time of instillation fluid delivered to the tissue site.
 8. The system of claim 1, wherein the processing element is further configured to modify the instillation therapy by adjusting the volume of instillation fluid delivered to the tissue site.
 9. The system of claim 1, wherein the processing element is further configured to modify the instillation therapy by adjusting the duty-cycle for delivery of instillation fluid delivered to the tissue site.
 10. The system of claim 1, wherein the processing element is further configured to modify the instillation therapy by adjusting the chemical composition of instillation fluid delivered to the tissue site.
 11. The system of claim 1, wherein the processing element is further configured to compare the pH of the wound fluids to a target pH range.
 12. The system of claim 11, wherein the target pH range is about 7.4+/−0.2.
 13. The system of claim 11, wherein the pH of the wound fluid is modulated by delivering instillation fluids to the tissue site that comprises any instillation fluid selected from a group of phosphate buffered saline, acetic acid, and soluble salts.
 14. The system of claim 13, wherein the pH of the wound fluid is modulated further by varying the concentration of the selected instillation fluid.
 15. The system of claim 1, wherein the processing element is further configured to provide a fluid-filled alarm when the pH of the wound fluid at the tissue site changes in proportion to the volume of instillation fluid delivered to the tissue site and reaches a value corresponding to a filled-volume of the tissue interface.
 16. The system of claim 1, further comprising a second pH sensor disposed at a second location between the negative-pressure port and the source of negative-pressure, and a second processing element electrically coupled to the second pH sensor for receiving a second property signal indicative of the pH of the wound fluids at the second location, the processing element being further configured to assess the health characteristics of the tissue site based on the pH of the wound fluids at the second location and modify the instillation therapy in response to the pH measured.
 17. The system of claim 16, wherein the processing element assesses the health characteristics of the tissue site based on a comparison of the pH of the wound fluids at the tissue site and the pH of the wound fluids at the second location, and modifying the instillation therapy in response to the comparison.
 18. The system of claim 17, wherein the processing element is further configured to increase the dwell time of instillation fluid delivered to the tissue site if the pH of the wound fluids at the tissue site remains substantially the same while the pH of the wound fluids at the second location decreases.
 19. The system of claim 17, wherein the processing element is further configured to increase the soak time of instillation fluid delivered to the tissue site if the pH of the wound fluids at the tissue site remains substantially the same while the pH of the wound fluids at the second location decreases.
 20. The system of claim 17, wherein the processing element is further configured to provide a blockage alarm indicating that the flow of instillation fluid is inhibited when the pH of the wound fluid at the tissue site changes, but the pH of the wound fluid at the second location does not change.
 21. The system of claim 1, wherein the system further comprises a controller configured to receive the property signals from the processing element and to assess property readings reflective of the property signals to identify the flow characteristics of the system.
 22. The system of claim 21, wherein the processing element further comprises a transmitter configured to transmit the property signals to the controller.
 23. The system of claim 21, wherein the controller is remote from the dressing interface.
 24. The system of claim 21, wherein the system further comprises an instillation pump configured to provide instillation fluid to the tissue interface, and a sensor electrically coupled to the controller and adapted to measure an instillation pump pressure provided by the instillation pump.
 25. The system of claim 21, wherein the system further comprises an instillation pump configured to provide instillation fluid to the tissue interface, and a sensor electrically coupled to the controller and adapted to measure an instillation duty cycle provided by the instillation pump.
 26. The system of claim 21, wherein the system further comprises an instillation pump configured to provide instillation fluid to the tissue interface, and a sensor electrically coupled to the controller and adapted to measure an instillation pump pressure and an instillation duty cycle provided by the instillation pump.
 27. The system of claim 26, wherein the controller is configured to assess the property readings and provide an alarm identifying a blockage state condition as one of the flow characteristics when the instillation pump duty cycle increases while the humidity remains substantially the same.
 28. The system of claim 27, wherein the controller is further configured to provide an alarm identifying a blockage state condition when the instillation pressure increases.
 29. The system of claim 26, wherein the controller is configured to assess the property readings and provide an alarm identifying a fluid leak state as one of the flow characteristics when the instillation pump duty cycle and the humidity remain substantially the same.
 30. The system of claim 29, wherein the controller is further configured to provide an alarm identifying a fluid leak state when the instillation pressure increases.
 31. The system of claim 26, wherein the controller is configured to assess the property readings and provide an alarm identifying a fluid leak state as one of the flow characteristics when the instillation pump duty cycle remains substantially the same and the humidity increases but not to a predetermined threshold humidity.
 32. The system of claim 1, wherein the therapy cavity further comprises a vent port adapted to fluidly couple the therapy cavity to a source of positive-pressure.
 33. The system of claim 32, wherein the pH sensor is disposed proximate the vent port.
 34. The system of claim 32, wherein the pH sensor is disposed outside the therapy cavity.
 35. The system of claim 32, wherein the controller is further configured to receive the property signals indicative of the pH from the processing element and to assess property readings reflective of the property signals to identify the health characteristics of the tissue site.
 36. The system of claim 35, wherein the processing element is further configured to transmit the property signals indicative of the pH to the controller.
 37. The system of claim 36, wherein the health characteristics of the system include a wound progression state within the system, and wherein the controller is configured to provide an alarm indicative of the wound progression state based on the property signals.
 38. The system of claim 37, wherein the controller provides an alarm indicative of the wound progression state when the pH increases or decreases.
 39. The system of claim 38, wherein the controller provides an alarm indicative of the wound progression state when the humidity and temperature change.
 40. The system of claim 38, wherein the controller provides an alarm indicative of the wound progression state when the wound pressure is critically affected.
 41. A method for treating a tissue site utilizing a system for providing negative pressure and fluid instillation therapy based on assessing properties of wound fluids at the tissue site, wherein the system comprises a tissue interface and a dressing interface having a housing including a therapy cavity, the method comprising: positioning the tissue interface at the tissue site, the tissue interface adapted to be coupled to a source of instillation fluid; positioning the therapy cavity in fluid communication with the tissue interface, the therapy cavity adapted to be coupled to a source of negative pressure; delivering instillation fluid from the source of instillation fluid to the therapy cavity; sensing pH of wound fluids using a pH sensor mounted to the housing in fluid communication with the therapy cavity; determining flow characteristics of the system by using a processing element electrically coupled to the pH sensor, wherein the processing element receives property signals indicative of the pH measured; and modifying the instillation therapy in response to the pH measured.
 42. The method of claim 41, wherein the pH of wound fluids is sensed within the therapy cavity adjacent to the tissue interface.
 43. The method of claim 41, wherein the pH of wound fluids is sensed within the therapy cavity adjacent to the tissue site.
 44. The method of claim 41, wherein the pH of wound fluids is sensed at a position between the negative-pressure port and the source of negative-pressure.
 45. The method of claim 41, wherein the instillation therapy is modified by adjusting the dwell time of instillation fluid delivered to the tissue site.
 46. The method of claim 41, wherein the instillation therapy is modified by adjusting the soak time of instillation fluid delivered to the tissue site.
 47. The method of claim 41, wherein the instillation therapy is modified by adjusting the volume of instillation fluid delivered to the tissue site.
 48. The method of claim 41, wherein the instillation therapy is modified by adjusting the duty-cycle for delivering instillation fluid delivered to the tissue site.
 49. The method of claim 41, wherein the instillation therapy is modified by adjusting the chemical composition of instillation fluid delivered to the tissue site.
 50. The method of claim 41, wherein the instillation therapy is modified by comparing the pH of the wound fluids to a target pH range of about 7.4+/−0.2.
 51. The method of claim 41, further comprising transmitting the property signals to a controller within the system for assessing the flow characteristics of the system.
 52. The method of claim 51, further comprising receiving the property signals by the controller, and assessing property readings reflective of the property signals to identify the flow characteristics of the system.
 53. The method of claim 52, further comprising sensing an instillation pump pressure and an instillation duty cycle of the source of instillation, wherein the instillation pump pressure and the instillation duty cycle are provided by sensors electrically coupled to the controller.
 54. The method of claim 53, further comprising using the controller to assess the property readings and provide an alarm identifying a fluid leak state as one of the flow characteristics when the instillation pump duty cycle increases and the humidity remains substantially the same.
 55. The method of claim 54, further comprising using the controller to provide an alarm identifying a fluid leak state when the instillation pressure increases.
 56. The method of claim 53, further comprising using the controller to assess the property readings and provide an alarm identifying a fluid leak state as one of the flow characteristics when the instillation pump duty cycle remains substantially the same and the humidity increases but not to a predetermined threshold humidity.
 57. The method of claim 41, further comprising transmitting the property signals to a controller within the system for assessing the health characteristics of the tissue site.
 58. The method of claim 57, further comprising receiving the property signals by the controller, and assessing property readings reflective of the property signals to identify the health characteristics of the tissue site.
 59. The method of claim 58, wherein the health characteristics of the system include a wound progression state within the system, and wherein the method further comprises providing an alarm indicative of the wound progression state based on the property signals.
 60. The method of claim 59, further comprising providing an alarm indicative of the wound progression state when the pH increases or decreases. 